Ripping Ligaments & Snapping Bones — Tech Binding Release Testing

Post by blogger | December 22, 2014      

Jason Borro

Tech Binding Release – Part 1: Introduction
While nearly all alpine and alpine-touring ski bindings have release mechanisms, skiers today can still be injured when bindings fail to release. For various reasons, there is silence and confusion within the industry and consumer public regarding the level of injury protection bindings actually provide. I decided to investigate, with focus on tech (pintech) bindings.

Quickly reaching the limit of standard ski shop release check tools, I reached out to Rick Howell of Howell Ski Bindings. Rick is an independent binding engineer and maintains a suite of research equipment designed to test ski binding release. His equipment simulates various standard release tests as well as investigate loads pertaining to the knee. The latter goes above and beyond the requirements of existing international standards. See our Wildsnow lay explanation of these standards.

We tested a variety of tech bindings using a Scarpa Rush boot with a BSL of 314 mm. Using one boot for all the tests eliminated the variance that can be seen across tech fittings due to manufacturing differences. SCARPA boots are equipped with Dynafit Quick-Step-In fittings which are thought to operate well with most tech bindings. In-person inspection of the fittings and observation of their release behavior verified this to be true.

Two dimensional binding release envelope graph.

Two dimensional binding release envelope graph. Click all images to enlarge.

Results of Howell’s testing are best displayed as graphs. Above, you are looking at a sample two-dimensional “release envelope,” generated by pulling laterally along a ski at increments of 10 centimeters. The boot is held fixed by a metallic rod that represents your tibia (main lower leg bone). Depending on scenario, a lateral force can be applied at various points along a ski, simulating torques applied to your leg.

The perfect binding would have a flat line in the graph, meaning it releases at the same tibia torque regardless of where the lateral force is applied. That line would be adjustable up or down based on an indicator setting. But as you can see, in the real world there are peaks and valleys in the envelopes. These peaks and valleys can lead to injury due to non-release. Bindings with lateral release at the toe (most alpine) and lateral release at the heel assisted by the toe (most tech) have different release envelope shapes which result in different injury profiles.

Tech binding release testing setup.

Tech binding release testing setup.

We tested both ski touring and skimo race bindings, with special emphasis on the latter (one pictured above). This is because race bindings without adjustable release have undisclosed permanently set release values that may or may not be appropriate for a given skier’s size and skiing style. We found these values varied greatly.

Another view of the test ski rig.

Another view of the test ski rig.

Tech Binding Release – Part 2: Lateral Release & Tibias
The tibia is the primary weight bearing bone in your lower leg (between knee and ankle). The tibia can break in two primary ways that are of concern to ski binding designers. One is a levered forward fall, or “bending” (covered in a later section), and the other is a twisting fall. (There is also a large combination matrix of twisting-bending falls, but for the sake of simplicity we won’t get into that here).

Tech binding release forces compared with alpine binding that releases laterally at toe.

Tech binding release forces compared with alpine binding that releases laterally at toe. The red shaded area on the right is the “blind spot” where the force required to generate a release can be greater than the approximate force required to fracture a tibia.

The lateral toe release mechanism on most alpine ski bindings is designed to mitigate bone injury when twisting is involved. However, the function operates quite differently depending on whether the binding releases laterally at the toe versus laterally at the heel. The chart above shows the forces required to initiate a release for an ordinary alpine binding and a sample tech binding (a race binding in this case). As you can see with the lateral heel-release binding (most tech bindings), the force required to generate a release can be greater than the approximate force required to fracture a tibia, labeled “Tibia Fx.” This is because, as could be expected, there is a lateral blind spot for such bindings centered on the toe piece, where the binding will not release. (In real life, you can feel this when doing a release “carpet test” of a tech binding while twisting your leg with emphasis on feeling resistance in the toe.)

Test rig for lateral release.

Test rig for lateral release, data was generated by pulling on a ski at 5 to 10 centimeter increments.

The graph was similar in shape for all the tech bindings we tested. The data was generated by pulling on a ski at 5 to 10 centimeter increments, which profiles the possible locations that forces could be centered upon. The data above proves that it is possible for some of these locations to simulate injury. (The data does NOT predict injury rates, since we cannot say how often things will end up in the red zone. This is left to epidemiology, more on that later. And, it should be stated we did not test “toe release” tech bindings such as Fritschi Vipec.)

Note: forces required to break a tibia near the toe piece are quite high and may not be easily achievable during normal skiing. This is because the distance between the applied lateral force and the axis of the tibia is relatively short. Shorter distances result in lower torques. Also, this laboratory result was generated on a weightless ski: it was not flexed as if in soft snow or loaded as if it was being skied. (Generating the above data at various degrees of ski flex and pre-loads results in a three-dimensional envelope, a more revealing and costly study.)

Tech Binding Release – Part 3: Knees
For our purposes, Howell employed specialized test devices to measure the valgus torques that are associated with ACL strain. Valgus is the biomechanical term for torque about the femur (bone between knee and hip), which is generated by sideways load on a ski. In lay terms, something like “twisted knee,” without lower leg twisting.

The test setup involved a metallic test knee bent at 90 degrees with the upper end of the femur fixed to a test frame. Attached was a metallic tibia and foot, sized for an average U.S. male, which was inserted into our test boot. The boot was clicked into a mounted test binding and the ski was pulled laterally while peak torques were measured during release. These loads were converted to ACL-strain utilizing a special algorithm and then compared to a theoretical ACL rupture limit of an average US male.

Sample result below. As you can see, we were unable to generate the strains necessary to rupture the ACL of an average US male using the Kreuzspitze SCTT race tech binding. This graph shows data within the “sour spot,” the region just behind the axis of the tibia (from -5 to -20 cm) which can produce large valgus torque as well as a small amount of internal rotation and torque about the tibia (think pigeon toes). The test results were similar with the other tech bindings we tested, with a couple exceptions for bindings that have non-adjustable release values that are too high for the average US male.

ACL rupture force  testing.

ACL rupture force testing.

Even in the exceptional cases, the force required to release the binding “poked through” the ACL rupture limit in only a small range of applied force locations within the sour-spot on the ski.

In contrast, ordinary alpine bindings release far over the ACL rupture limit using this setup. This is because basic lateral-toe release design has a lateral blind spot at the heel (opposite situation compared to heel-release tech bindings, with blind spot at the toe), preventing the ski from releasing in these types of simulated injuries. (Some alpine bindings in development that attempt to correct for this by releasing laterally at both the toe and heel. For full disclosure, two of these bindings were designed by Howell.)

To visualize the complete difference between a tech and alpine binding, see the graph below. The grey lines are a full 2D lateral release envelope of a popular touring tech binding. It includes both tibia release torques and valgus release torques. Overlaid on the graph in reddish is data from an ordinary alpine binding. Each black dot shows the peak release torque for a given applied-force along the length of the ski. The dots are connected to form a release envelope. Each binding design produces a unique signature. Both lateral-toe and lateral-heel release designs earn an “OOPS”, the former for knees, and the latter for tibias. You can pick your poison to some degree, but neither binding design will fully protect you from injury.

Tech and alpine bindings compared.

Tech and alpine bindings compared.

Tech Binding Release – Part 4: Vertical (Forward/Upward) Heel Release
This mechanism on most tech bindings relies on the force required to separate two heel pins the required distance to slip through escape channels in the boot fitting. For non-adjustable race bindings, the force required to actuate a forward release is determined by the kinematics of the binding design and by metallurgy.

Vertical heel release with most tech bindings is a matter  of metal pins sliding through a boot fitting.

Vertical heel release with most tech bindings is a matter of metal pins sliding through a boot fitting.

We found that race bindings we tested had forward release values running the gamut of possibilities. The values were often different than their lateral counterparts. The lightest binding we tested actually had the highest forward release value. It would probably have an indicator value near 15 if it were adjustable.

The chart below, based on a sample adjustable touring tech binding (not a race binding), compares indicator values to standardized release values. The indicator progression is nicely linear when it comes to forward release, but it consistently tests higher than the ISO standards would expect.

Tech binding forward release values as indicated by numbers on binding, compared to  ISO standard.

Tech binding forward release values as indicated by numbers on binding, compared to ISO standard.

This is consistent with values we see in shop tests. So before you jack up the vertical release on your tech binding on a whim, consider for a moment that it could already be higher than you are led to believe by the numbers printed on the binding.

Tech Binding Release – Part 5: Epidemiology and Conclusions
After scary injury discussions such as those above, it’s important to get some perspective on the frequency of injuries. Below is a table from a 2012 edition of the American Journal for Sports Medicine, containing the latest data from the well-known Johnson and Shealy study at Sugarbush. (For more information regarding Johnson and Shealy, try this link, and this.)

Alpine resort skiing injury study.

Alpine resort skiing injury study.

These are injuries that occurred to adults at a resort, primarily on alpine bindings. As you can see, knee injuries are still a problem with ordinary alpine bindings. Tibia fractures, now at around 1.3% prevalence, did not make the top 10 list. Years of biomechanical research and corresponding binding design drastically improved the incidence of that type of injury. That engineering work has since been integrated into various national and international standards.

If lateral-heel release tech bindings became the in-bounds standard, I would predict a tick up in tibia injuries and a tick down in ACL injuries (assuming bindings are adjusted to appropriate levels).Thankfully, the mean time between all types of injuries is luckily large enough to enjoy a lot of turns between them.

For now, I am happy to report that we accomplished our original goal of this biomechanical testing, which was to help skiers find a binding that may be most appropriate for them. With over 1000 release tests performed on a half-dozen models, we are more confident in guiding folks into bindings based on their size, skier type, and intended use.

I also programmed a release calculator with this notion. Reliable information about the release of tech binding models is especially useful in the skimo world, since many endurance athletes are taking up racing without a strong skiing background — but to compete near the top, they need a foreign binding with undisclosed release mechanics.

Important: This discussion is entirely about release. However, many folks believe that retention is still far more crucial when it comes to overall safety. Retention failures can lead to serious injuries or worse. Skiers on tech bindings in “no fall” situations are often better off locking their toes and setting high release values to prevent lateral and roll release. The tech binding locking mechanisms tested admirably if judged by the strains and groans produced by the testing equipment. (Note that locking a tech binding only locks lateral release, while vertical “up at the heel” release values remain the same.)?

( guest blogger Jason Borro is the owner of Skimo Co, a ski mountaineering specialty store. Being a software engineer, Jason is a terrible salesman and built an online store filled with obscure European widgets skiers don’t yet know they want. He is currently focused on unlocking the mysteries of tech bindings. He has titanium in his tibia because it’s lighter than steel.)



333 Responses to “Ripping Ligaments & Snapping Bones — Tech Binding Release Testing”

  1. Lou Dawson 2 December 22nd, 2014 8:19 am

    Editor’s note: I agreed to a strict editorial lock on the body copy of this blog post, so I’ll put my editor’s note here in the comments.

    Jason worked really hard on this, then it went over to our editing process here at WildSnow, and finally got a nod from Rick as well. Took a while but it was worth the work.

    I’ve always suspected that tech bindings were a bit less forgiving as to tibia bone injury from twisting falls, but actually less risky for your knee ligaments due to the side release at the heel. I’m delighted to see my suspicions validated.

    Jason and Rick also verified that tech binding release settings can easily end up higher than you might want or need. Pay close attention to that, and remember that tech binding lateral and upward release can be set independently. Thus, you can fine-tune.

    Along with all this, I continue to wonder if it might be wise for ALL users of tech bindings to check their release settings using a shop tool instead of blind faith in the numbers printed on the bindings. For active skiers running multiple sets of bindings, that would seem much wiser than risking having one set of bindings that perhaps does a pre-release due to whacked out settings, causing you to dial up all your other bindings when you actually don’t need to do so.

    I’m sure Jason will address some of these ideas, and perhaps Rick as well.

    In any case, thanks Jason for your work on this! And thanks Rick for paying attention to our little corner of the ski binding world!


  2. Tuck December 22nd, 2014 8:56 am

    Fascinating. Thanks to all for doing all this work!

  3. SR December 22nd, 2014 9:38 am

    Extremely impactful stuff, thanks to all involved in this!

  4. Lou Dawson 2 December 22nd, 2014 9:52 am

    I should mention that in the ski world we loosely define “tech” binding as one that utilizes the boot fittings originated by Dynafit. Currently, some tech bindings do not use the boot heel fittings, example being Marker Kingpin, and Kingpin was not tested. ALSO IMPORTANT, the article above pertains to testing “tech” bindings that use both the toe and heel fittings, with lateral release at the heel. Example, Fritschi Vipec would still be called a “tech” binding but it does not release laterally at the heel, the release is at the toe, and any assumptions or extrapolations from this article do NOT apply to Vipec.

  5. TimZ December 22nd, 2014 11:33 am

    Do you plan on releasing the estimated RV of race bindings? Maybe just on a scale of lower to higher without giving actual numbers(since I do understand liability plays a huge role in this)?

  6. dave bass December 22nd, 2014 11:35 am

    Fascinating! but did I miss something?
    I was hoping for a chart documenting the approximate tested release values of tech race bindings that lack adjustability.

  7. VT skier December 22nd, 2014 11:43 am

    Very good stuff!
    I wonder if a modern telemark binding (oxymoron?) would show even lower ACL injury rates, as the boot is effectively in a forward release at all times.
    Anecdotally, with the Rotte Freeride and Freedom bindings, I have had effective release with my heel held down on the ski, but a less reliable release (or none at all) when my heel is raised off the ski.

    It would be interesting to see some testing on these two Telemark bindings, but sample size (of users) is probably too small.

  8. Rick Howell December 22nd, 2014 11:53 am

    Hello fellow skiers—
    As noted in the graphs, the lateral ‘release values’ of pintech race bindings vary, greatly, for any given ‘setting’ — as a function of where the lateral force is applied to the ski. That’s the point being made. With a ‘good’ alpine binding, the release value is relatively constant (parallel to the tibia fracture limit), irrespectively of where the applied lateral force enters the ski (again, please see graphs, above). Therefore, when we measured the ‘release values’ of the 6 different brands of sample pintech race bindings, we found that the resultant torque on the tibia (and the applied-force at release) changed significantly — depending upon WHERE the applied-lateral-force enters the ski. This means that the so-called ‘release value’ of a pintech binding does not correlate to a constant (or even to a ‘near-constant’) resultant torque on the leg (again, please see graphs, above).

    If you are interested, I can explain how the lateral forces end-up entering the ski in different places. The explanation is based on direct loading analysis (on-snow) — and more significantly it’s also based upon an inverse analysis (injury forensics). Both approaches arrive at approximately the same conclusion about the fact that lateral forces can enter the ski in a wide range of positions during various types of ‘events / falls’.

  9. Rick Howell December 22nd, 2014 12:03 pm

    @ VT Skier:

    Ethical standards for human subject testing does not permit the utilization of real humans in ski-binding release tests. That’s why we perform engineering-grade release tests with a physical-experimental simulation that applies a ‘full envelope’ of test conditions (every possible loading scenario — please see the full-range of test conditions in the graphs) utilizing an instrumented metallic leg (measuring tibia-torque, valgus-torque, applied force, and position of applied force). The measured-values at release (for an average skier) are then compared to previously-known biomechanical limits (for average humans) (see graphs that identify the biomechanical limits and the binding’s release-limits, overlayed together).

  10. jbo December 22nd, 2014 12:39 pm

    TimZ & dave bass – Thanks for the interest. I may publish a chart with all the appropriate disclaimers (see Rick’s comments to begin to understand why this may not be a good idea). I need to do it somewhere I can edit frequently though (e.g. on, as these things are a bit of a moving target. Inline changes can make half of your stock one “number” and half another.

  11. Rick Howell December 22nd, 2014 1:03 pm

    @ jbo: There cannot be a ‘chart’ because the so-called ‘release values’ — unlike the so-called DIN-values utilized in alpine binding testing and numbering — vary as a function of where the lateral forces are applied along the length of the ski. As a co-author of the DIN-System, I can say that the so-called DIN’s rely upon a ‘flat’ envelope, not the sloping envelopes shown in the graphs. Therefore, any ‘chart’ that seeks to do as you suggest is not providing information to skiers or to retailers that has meaning in terms of expected release under a wide range of event / fall conditions that occur on-slope.

    I do realize that the above data introduces new concepts that will take time to digest their full meaning … but there are no ‘DIN’ numbers that can be extracted from testing pintech bindings BECAUSE the standards that provide the basis for the numbering system rely upon a binding that allows the ski to release about a point that is located under or near the projected axis of the tibia. In the absence of a pivot location under or near the projected axis of the tibia, ‘DIN’ numbers cannot apply. This is not a ‘disclaimer’, these are engineering facts that re-classify pintech bindings — with their own unique disadvantages and advantages. Please do not try to fit a round peg into a square hole: these two types of bindings are apples and oranges. Perhaps pintech bindings should have a different release identification system such as, maybe ‘a’, ‘b’, ‘c’, ‘d’; or, ‘apples’, ‘oranges’, ‘bananas’, etc. — so that there is no confusion about how these two different types of bindings (alpine and alpine-touring) apply completely different loads to the leg under the same loading / fall -conditions.

  12. TimZ December 22nd, 2014 1:24 pm

    Thanks for the consideration Jason. I do understand that this is complex on many fronts.

    The curve is not flat: Yes, but it seems implied that the ATK SL-R(Hagan ZR, etc) has a similar curve shape to the Trab TR Race, but with a higher force to release at each location. It would be interesting to see a comparison that perhaps compares the given race bindings in order from lowest force to release to highest force to release.

    For example, I would not have gone with the ATK SL if I knew the fixed RV was so high, and I imagine there are other consumers who would take the relative RV into consideration if that information were public.

    Happy holidays to all!

  13. Charlie Hagedorn December 22nd, 2014 1:28 pm

    From a liability perspective, you could consider posting the peak release force and integrated impulse-to-release for each binding tested, instead of quoting a “release value”.

    For the pin-tech heels, it should be relatively straightforward to provide a chart of the force at the heel pins as a function of displacement laterally and vertically. That should be fairly general and interpretable. Characterizing toepieces is trickier, but a lateral measurement could provide some insight..

    Thank you for the article. It’ll take some time to digest the plots.

  14. JonB December 22nd, 2014 1:44 pm

    Very interesting. I would be greatly interested in learning how lateral forces enter a ski in different locations. I imagine it would have to do with how flexed the ski is when the force is transmitted, what caused the force (hitting an obstruction with the tail of the ski in a skidded turn vs. a fall, etc.).

    The only time I hurt myself using a tech binding was following a traverse track in a near white out. The track took a rapid turn to the left that I could not see because of the poor viz. The tips of my skis slammed into the wall of the slope and my heels did immediately release (the toes did not), but I hurt my knee somehow. It wasn’t an ACL or MCL. Might have just been hitting the deck of the ski with my knee as I rotated forward around the binding pins. It took about a week before most of the pain was gone. I never bothered to go to the doc because I didn’t get back home before most of the pain was gone, but I’d be interested to find out what the actual injury was. I surmise it was likely a small meniscus tear.

  15. VT skier December 22nd, 2014 2:42 pm

    I wrote earlier,
    “It would be interesting to see some testing on these two Telemark bindings, but sample size (of users) is probably too small.”

    What I meant was the number of users, ie people skiing these two releasable NTN telemark bindings, the Rotte Freeride and Rotte Freedom is so small that market share wouldn’t justify the research.
    I didn’t mean to imply that actual skiers be used as crash test dummies, to evaluate the bindings at various release values!

  16. Rick Howell December 22nd, 2014 2:48 pm

    @ VT skier: Ahhhhh….. Yes….. Sorry about that ! I’ve got it now 🙂

  17. Jim Milstein December 22nd, 2014 3:03 pm

    Taking Lou’s suggestion, I went to a local shop and had my Vipecs tested against the DIN chart. With the bindings set at the bottom of the Vipecs’ DIN scales, 5 at both toe and heel, the release torques were slightly over double the DIN chart values. According to the chart, these are torques suitable for a very much larger person.

    That was interesting. Not entirely sure what to think. As mentioned on another thread, no releases, pre or otherwise for me.

  18. Lou Dawson 2 December 22nd, 2014 3:14 pm

    Regarding the tele bindings, if they’re set up high enough not to pre-release I doubt they have much in the way of meaningful values in terms of release forces. What is more, at what heel height would you test the binding? Every change in heel height would change the force required for release. Can of worms. Lou

  19. See December 22nd, 2014 3:15 pm

    I don’t have experience with race tech bindings, but it seems offering a range of swappable parts would enable users to set appropriate rv’s without the added weight of the adjustment mechanisms.

  20. Lou Dawson 2 December 22nd, 2014 3:20 pm

    Rick, I hear you about ethical standards, but in the DIN/ISO 9462 they do require human field testing for “unwanted release.” With supposedly properly adjusted bindings, but I’ll bet there have been a few “inadvertent ejections” during the field tests (grin).

  21. Lou Dawson 2 December 22nd, 2014 3:22 pm

    All, apologies for some of Rick’s and other’s comments that got held up while we were out skiing (binding testing, as we now call it). To avoid our moderation tank (trying to prevent comment spam), don’t use any special characters and don’t use emoticons. You might still get held up, but not as likely. Lou

  22. Rick Howell December 22nd, 2014 3:42 pm

    Yes, Lou, as one of many co-authors of ISO 9462, testing is conducted on-snow significantly — but NEVER for release. We test on-snow ONLY for pre-release (only AFTER extensive standard laboratory retention testing and AFTER extensive proprietary laboratory retention testing); AND we test on-slope for durability. NEVER for release. In our on-slope retention tests, I once popped my spleen (internally hemorrhaging nearly half of my body’s blood before surgery; seperately, knocked-out 4 teeth; and have sustained several concussions testing bindings). Each such event was AFTER we were SURE, in the lab (the proprietary lab tests are actually quite ‘telling’). My point: please, do not attempt any kind of ski-binding ‘testing’, yourselves … but, yes, we do on-slope testing as noted to develop new binding designs.

  23. TimZ December 22nd, 2014 3:43 pm

    Re: See

    I don’t have testing tools, but some forks do fit other brands bindings. However they all seem to have different lengths, so testing would require non reversible changes to test for different RVs

  24. TimZ December 22nd, 2014 3:45 pm

    Re Rick:

    What I, and I expect others, are asking for is not a DIN. I am asking for a rough estimation of a release value. I do not plan on comparing this # to DIN values. I do plan on comparing this # to other pintech release values of similar engineering design.

  25. Lou Dawson 2 December 22nd, 2014 3:46 pm

    Tim, Dave and others. To provide a usable chart of measured release values for a binding would require sampling a variety of bindings. The DIN/ISO standard itself requires, for example, “4 bindings randomly chosen from a set of 6 bindings.” After that, if the bindings matched fairly close in release values perhaps the values could be averaged, but what if one binding was way whacked out (that’s an engineering term), what good would it be to average, or report? What’s important is if you’re concerned about safety, is to get your bindings tested with a machine so you at least know what you’re dealing with. Even the DIN/ISO standards don’t require the set release resistance of the binding to be super exacting in matching the printed numbers, it’s assumed the binding will be tested and set by a shop employee. Lou

  26. Lou Dawson 2 December 22nd, 2014 3:52 pm

    Rick, a couple of the worst falls I’ve ever taken have been while “testing” bindings during demos and getting inadvertent release. Even happened a few years ago at a press event, re-injured a shoulder I’d had rebuilt… I still “evaluate” new bindings but I don’t push them so hard I could say I’m “testing” them. What you’re saying validates that, thanks. Life as a ski “journalist” requires being on whoop-de-doo new bindings now and then. Only safe approach I’ve found is to set the release values high, don’t fall, and don’t ski too aggressively. Oh, and have good insurance. Lou

  27. Rick Howell December 22nd, 2014 4:03 pm

    @ Lou—

    Respectfully, testing a large sample size of pintech bindings will not change the binary nature of pintech bindings’ release CHARACTERISTICS relative to alpine bindings’ release CHARACTERISTICS. From the above tests we now know that ski-shop measurements will have no salutary effect toward mitigating tibia fracture under a broad spectrum of loading conditions when utilizing pintech bindings: even a pintech binding that is functioning according to manufacturer intentions can easily generate injury-producing loads on the tibia. Please see that ‘release CHARACTERISTICS’ (shape of the release envelopes) is mutually independent of ‘release SETTINGS’.

    As for on-slope testing: again, this is serious business: one of my ski-racing colleagues, Kent Yale, died from pre-release; and one of my co-workers in the ski binding business is quadriplegic from pre-release. However, the Good News is that new ski bindings that are engineered via ‘Axiomatic Design’ principles are hard-pressed to pre-release in any conditions even at chart-settings.

  28. Lou Dawson 2 December 22nd, 2014 4:05 pm

    Jason, to be fair to the companies (and truly useful) you’d need to test perhaps 4 or more of each binding, preferably from a different manufacturing batch. If you don’t do that and publish numbers I don’t see how they’ll be anything but misleading. The printed numbers on bindings are bad enough, what if a chart says “5” but some bindings are “7”? … Another factor here is that as a tech binding releases over and over again laterally, the boot fittings get wear, which in my opinion changes release values and definitely changes retention behavior. Again, the only way to control for this in real life is to have a person’s individual boot/binding combination tested, specifically for them. Lou

  29. jbo December 22nd, 2014 4:06 pm

    TimZ – Well said about choosing a binding; that was the impetus for this testing. Despite not being currently published, the numbers are known. We have full charts for each tested binding.

    Charlie – As you can see in the charts, the peak release force is off them! The toes play a role in the release so plotting heels separately isn’t terribly informative.

    JonB – It is obviously hard to predict where the sum of forces ends up being centered, but it involves ski shape, loading, terrain factors, etc.

    Rick – Thanks for reinforcing the main point. I was not suggesting a DIN table, just a comparison of all the graphs we collected, with binding names.

  30. Lou Dawson 2 December 22nd, 2014 4:08 pm

    Rick, point taken about CHARACTARISTICS. I’m only addressing the fantasy of somehow having useful charts that give specific accurate torque or force measurements for a given binding model.

  31. Kristian December 22nd, 2014 4:15 pm

    Found this out the hard way.

    Several years ago, while watching friends skiing below from a summit, I was drifting forward at about .5 mph. Minor awkward fall popped my ACL and it was suddenly a grim epic to self evacuate from several miles into the backcountry.

    Wrapping my leg and knee with my climbing skins greatly helped to immobilize it.

  32. Rick Howell December 22nd, 2014 4:17 pm

    @ TimZ—

    Thank you, Tim, for your good request. I agree that what you are seeking is vitally important.

    The above graphs provide all of what you are seeking: Jason correctly notes that the differences in “release [characteristics]” between the various brands of pintech bindings are ‘similar’. Jason has more exacting information within his good website. Jason can also be reached, one-on-one via his Skimo website.

  33. jasonq December 22nd, 2014 4:27 pm

    I’ve long had an interest in ski binding design and lower leg mechanics. I did my honors thesis in releasable telemark bindings in the early 90’s and went on to do bio-mechanics research on bone mineral gain and loss and resulting injuries with focus on zero G and rehab at NASA. While my knowledge is no longer current, at that time, i was far more that just passingly acquainted with binding theory and release/retention envelopes.

    A few observations on this work:
    -I did not note the issue of lateral release at the heel, aka rotation about the toe, causing the tibia to be both in torsion AND bending. While with lateral release at the toe, rotation about the tibial axis, the tibia is only under torque. In other words, the overall tibial loading is higher for the same tibial torque when lateral release is at the heel. So lateral release around the heel can result in tibia fractures at lower torques than around the toe due to the added bending stresses. (extensive research on this topic including that done by prof CD Mote at Berkeley in the 80’s. I believe Pizziali (sp?) also did experimental work on this using cadaver tibias at stanford around the same time. )

    -everything presented is static loading. The ski-leg system unfortunately has a natural frequency of right around 1 hz, which is smack in the middle of common frequency inputs while skiing. This is why energy absorption is so important. Its a complicated topic, too complicated for general consumption and adds another dimension to release envelopes, but the important part is energy absorption comes in two basic forms, elastic (as in stored in a spring), and friction. Both will keep your ski from chattering off, but friction is not desired for many reasons not the the least of which is that it affects the release values.

    Bringing the two points above into account, forward or backward twising falls can be especially trouble some for lateral release at the heel. In forward twisting, both the lateral and vertical release torques can be below threshold while the stress on the tibia can be well above fracture. Toss in friction and it can get worse. Luckily, pintech bindings have most of the friction sources contained and controlled in the heel unit, and don’t really on much sliding contact of uncontrolled surfaces (minimal friction between the heel fitting and heel pins). But the Ramer bindings that served as the inspiration for the dynafit designs were another story. They had significant frictional loads especially in a forward twisting fall, making those bindings especially prone to tibia fractures in forward twisting falls (Note: I seem to remember Lou had a spiral tibia fracture from a forward twisting fall using a Ramer binding).

    finally, even back in the early 90’s there was work on smart bindings that triggered release using sensors and predictive models, I am still surprised that 25 years later, we are still using springs and geometry to trigger release. Where is my fly by wire binding?

  34. Rick Howell December 22nd, 2014 4:34 pm

    @ JonB—

    This is an excellent question. To avoid ‘predicting’ positions of applied lateral loads on the ski, binding engineers test all possibilities. This way, we can see the ‘worst-case scenario’ and deal with it from a design-engineering perspective.

    Lateral loads enter the tip (or, alternatively — the tail) of a ski when one end of the ski slides-out. This happens with ‘straight’ skis. However, with shaped skis, both ends bite (one end does not slide-out): in this way, the resultant of the lateral loads that are applied at the tip and tail resolve to become a single ‘centroid’ located near the center of the ski. Applying lateral loads to the center of the ski simulates the single centroid that’s produced when both the tip and the tail do not slide-out. This is analgous to a beam that produces a single force in it’s center, even though the 2 columns at both ends hold 1/2 of the weight of the beam. That’s how a lateral load can become applied on-snow near the center of a ski. It is this loading-postion — between -5cm and -20cm aft of the projected axis of the tibia (combined together with a small dash of rear-weighting) that ruptures the ACL during so-called Phantom Foot or Slip-Catch injury mechanisms. Other lateral loading positions along the length of the ski do NOT cause the ACL to rupture. (( Sub-note: however, pure backward loading of sufficient magnitude can rupture the ACL. )) Phantom Foot and Slip-Catch ACL-injury mechanisms are believed to have a prevalence of ~80% of all skiing-ACL injuries, while pure backward loading (BIAD, which is an acronym for Boot Induced Anterior Drawer) is thought to have a prevalence of ~8% of all skiing ACL injuries.

    Testing all possibilities (the full 2D envelopes shown above) provides biomechanical data to illuminate the interaction between all loading scenarios and ski binding release CHARACTERISTICS ( not ‘SETTINGS’; not ‘SAMPLE VARIATION’ 🙂 🙂

  35. Rick Howell December 22nd, 2014 4:53 pm

    @ jasonq—

    Dan Mote at UC Berkeley and Bob Pizialli (one of Dan’s PhD students) are my colleagues.

    Respectfully, neither Dan or Bob studied combined torsion and bending loading, experimentally relative to torsional tibia fracture ( I have ALL of their papers. Sorry. 🙂 🙂

    Worst-case loading for release is quasi-static. Dynamic loading (where inertia is significant) is about retention. Bones and ligaments are visco-elastic: they become approximately 18% stronger during dynamic loading. We binding engineers focus on the worst-case scenario: that scenario is quasi-static, NOT dynamic loading. Sorry.

    Please do not dilute this important quasi-static worst-case release data regarding standard industry practice relative to tibia integrity with information that’s not relevant to this important discussion about ‘release’. Pintech bindings (or any binding that has an axis of rotation near the front of the boot) do NOT uniquely induce additional forward or backward bending moments beyond the lateral loading that’s exhibited in the above envelopes.

    As for quasi-static friction, this is why a ‘margin’ is needed. Friction is never good under any circumstance: It must always be mitigated. As for dynamic friction, this was my thesis on ski bindings at MIT’s Charles Stark Draper Labs; in-practice when I worked 8-years at Geze ski binding company (acquired, indirectly, by Rossignol) and when engineering the 1st clipless bicycle pedals, CycleBinding. Mitigating friction is critical. However, the resultant effects on the tibia as function of the position of lateral (abduction) loading is the fundamental 1st-order of business …. because if this aspect is incorrectly addressed in ski binding engineering, all of the ‘Good Intentions’ of essential friction-mitigation become moot. The above data is primary to the functional requirements of proper biomechanical function in all forms of ski bindings (your body does not know if you’re utilizing an alpine-touring or alpine binding). (( Also, please remember that a binding that provides lateral release at BOTH the toe AND the heel combines the best of both worlds when it also does NOT pre-release. 🙂 🙂

  36. Rick Howell December 22nd, 2014 5:05 pm

    p.s. — Dan Mote is presently president of Univ. Maryland 🙂 🙂 and his ski-binding research was great ( it resulted in ISO 9465 ).

  37. Rick Howell December 22nd, 2014 5:35 pm

    @ jasonq —

    All major binding companies have invested fortunes on electronic bindings with microprocessors. Several binding companies have had multiple decade-long spurts of developing such bindings with 2-year rest periods in between. At the end of the day, 3 things have hampered this development: (1) reliable power at -30°F after being stored in the condo mandatory outside condo locker; (2) which loads to measure; (3) the biomechanical limits. We’re beginning to get a handle on #’s 2 and 3 …. but the 1st point (reliable power during long periods of cold) remains a problem. I’m comfortable with my data regarding #’s 2 and 3 (the other binding companies are about 2 to 4 years behind me in this way) … but I’m fully-uncomfortable with problem #1. Additionally, from a commercial perspective, a mech-tronic binding must have a 100% mechanical back-up system (remember Fukamora) … and to have both a mech-tronic AND fully mechanical binding all in one presents a cost-of-goods-sold and/or margin problem. A sustainable binding company cannot have a COGS or margin problem (witness one M ajor ski binding company with 4 bankruptcies due to COGS and margin issues). 🙂 🙂

  38. Rick Howell December 22nd, 2014 5:50 pm

    @ Charlie Hagedorn: Thank you for your good thoughts. The good tests that you kindly suggest help during manufacturing tolerance compliance verification … but those kinds of tests do not tell us about the interaction between the musculoskeletal system and the bindings function. I agree with Jason Borro at Skimo — the best way to evaluate this interaction is to measure the effect of a wide range of loading scenarios on the leg (tibia and ACL) as plotted in the graphs, above.

  39. Lou Dawson 2 December 22nd, 2014 6:03 pm

    Just to remind everyone, classic tech bindings (with the two pins at the heel inserted in the boot) compensate for ski flex by the steel boot fitting riding front/back on the rear pins. As the boot moves on the pins, the release value changes. The closer the boot the higher the value, until the boot gets so close it jams against the binding. This is why binding makers have been battling to make tech binding heels that move fore/aft under spring loading, like most alpine heels. Me, I prefer the original elegant simplicity of the boot riding on the pins, but alas, no way that’ll perform well enough for TUV… What is more, it shows how complex this testing can get. Lou

  40. Rick Howell December 22nd, 2014 6:21 pm

    Yes, Lou — agreed: it’s easy to make a product simple when one skips half of the design requirements.

    The hardest part of product design is to make it simple.

    Testing also needs to be simple in order to generate reproducibility over the long haul — especially at the extreme ends of the spectrum ….. children’s bindings and real WC racing bindings.

    The above tests are simple.

    (( BTW, TÜV has no ‘requirements’: TÜV tests according to standards produced by ISO. ISO standards are produced by us. Each of us has a say. You should participate in this way, Lou. ))

  41. See December 22nd, 2014 7:28 pm

    Tim, I should have been clearer in my earlier comment. I wasn’t suggesting swapping parts among different models/makes of bindings. I was marveling at how (as far as I know) race binding manufacturers don’t seem to make, say, light, medium and stiff forks etc.. A “one size fits all” approach to binding design is a bit nuts, imo.

    I’ve never disassembled any of the bindings in question, but I suspect swapping a “light” fork for a “stiff” one (for example) wouldn’t be that tough in many cases. (Testing, of course, still a good idea if you can find some who can do it.)

    Re. friction— I sure wish I could get a set of brakes with the sliding afd for my Verticals. I’m considering looking into drilling out the rivets on some Radical brakes and trying to mount them on the Verts. Any one tried this?

  42. Pablo December 23rd, 2014 2:53 am

    Great Post!
    So, so interesting! but most interesting yet are the comments!!!
    Thanks, thanks you all, Lou, Jason, Rick and all the other comments.


  43. Pablo December 23rd, 2014 3:00 am

    Thinking about that electronic binding and it power supply, I think it’s posible to develop a portable battery sistem similar to those os heatable insoles.

    Yo could carry a 2000mh battery easily on top of your boots, charge it every time you go to ski an just conect it to the e-binding by a small cable sistem wich can detach when falling.

    I think this is a possibility to make posible a reliable e-binding.

    apollogies for my english, hope you understand me.


  44. altis December 23rd, 2014 4:04 am

    As an electronic engineer, I have to say that I would never, ever buy a set of bindings that relied on a microprocessor.

    I know this is hugely difficult to quantify but can anyone comment on the effects of snow, ice and wear on pintech vs conventional alpine bindings. In our time, we’ve all tried to stuff worn boots with snow-covered soles into conventional ones but my gut feeling is that pintech bindings are more sensitive. At least most users will have the benefit of experience before progressing to pintech.

    My own preference would be for a reliable, rigid boot/binding interface at both toe and heel (eg. pins and dimples) with the release mechanism based on springs and levers built into both parts of the binding – like a double-ended Vipec.

  45. Rick Howell December 23rd, 2014 7:19 am

    @ Kristian —

    ‘Trust you are ‘ok’ now — and that you are skiing as much as possible these days.

  46. Rick Howell December 23rd, 2014 7:20 am

    @ Pablo — Your English is far better than mine 🙂 Thank you for your thoughtful comments.

  47. Rick Howell December 23rd, 2014 7:28 am

    @ altis — These are great ideas you have. To echo your thinking — but in alpine-skiing — in my new alpine bindings, I have (utilizing your term) ‘double-ended’ alpine binding technology, jazzed it up with improved edge control, and tuned and refined it … to flatten the release envelope for both tibia-torque and valgus-torque on both the forebody and the afterbody of the ski. With this approach, we can have it both ways — tibia-friendly and ACL-friendly skiing.

  48. Mike December 23rd, 2014 8:46 am

    Am I right thinking that this analysis suggests that new marker binding (with tech toe and dh heel) would be the “worst of both worlds” due to the lack of lateral release at the toe or heel?

  49. Sandy Detillieux December 23rd, 2014 9:18 am

    How does the Diamir Vipec compare with regular “pintech” bindings for safety release and reliable retention?


  50. Lou Dawson 2 December 23rd, 2014 9:26 am

    Fritschi claims they are much much better, I don’t know of any comparative testing. Since they release at the toe they might have less of the bone breaking force at a certain point, but since they don’t release sideways at the heel perhaps they don’t protect your knee as well. Who knows, really. Lou

  51. Rick Howell December 23rd, 2014 9:27 am

    We have not tested that binding, yet, but we should.

    (( Also, the terms ‘safety’ and ‘release’ are a bit of an oxymoron. Please note that I do not utilize the term, ‘safety’, above 🙂 🙂

  52. Lou Dawson 2 December 23rd, 2014 9:44 am

    Thanks for the hint about the word “safety” Rick.


  53. Rick Howell December 23rd, 2014 9:49 am

    It costs $5,000 to conduct the tests necessary to generate a full 2D release envelope for both tibia-torque and valgus-torque for any given specific binding sample.

  54. Lou Dawson 2 December 23rd, 2014 9:57 am

    Mike, the Marker releases to the side at the heel, very nicely, let’s nip that misconception in the bud! Lou

  55. Lou Dawson 2 December 23rd, 2014 9:59 am

    Kickstarter, Rick’s test of Vipec and other bindings, who’s in?

  56. Chris December 23rd, 2014 10:48 am

    Kickstarter? How about if Fritschi ante up?

    I just bought, for several reasons, some Vipecs to try out. I would be most interested in knowing if they provide any substantial increase in safety. In my mind, they are currently the only offering that gets close to the weight of the Dynafit or Plum that provides additional safety features for; skinning up (they will release before pulling your knee apart), more elasticity to prevent pre-release, and possibly safer release characteristics when you need it. With all the other current “touring” pin bindings the weight penalty seems to great to me with no real improvement in overall “safety” or difference in release or elasticity characteristics if you prefer. IMO the real weak link in the standard pin binding is when the ski is loaded and the heel pins slide further into the boot and the RV goes through the roof or no release at all -the compressed, slow, twisting fall. I’ve experienced this a few times and I’m 180#’s and a RV of 7. Other than that potential major problem the Dynafit or Plum perform quite well and I would give the Plum a plus for durability after using them hard for two seasons.

  57. Charlie Hagedorn December 23rd, 2014 10:55 am

    To continue a sub-conversation:

    Full-suite binding testing is complicated and hard to interpret, but to compare two race heels that use the same heel interface, the heel-pin force vs displacement curves (horizontal and vertical) would be very useful.

    It won’t save the world from injuries, but it would help to inform buyers who are mixing and matching binding parts.

  58. Rick Howell December 23rd, 2014 11:34 am

    @ Chris, What is ‘safe’ ?

    @ Charlie, Jason Borro at Skimo has all of the release data to make the comparisons that you are seeking, independently of torque-rotation or force-displacement data. Jason Borro has all of the peak-loading data — both in terms of peak ‘applied-force’ as a function of position of applied force (at release) — and in an equal-magnitude-opposite-direction (action-and-reaction) perspective, Jason Borro also has all of the peak torque-about-the-tibia (at release) and peak valgus-torque (at release) data that you need to make an informed decision about what you are ultimately seeking.

  59. Mike December 23rd, 2014 11:59 am

    Thanks for clarifying Lou. Any chance you would be able (time permitting) to post a video similar to the one you did for the beast showing lateral release function for the kingpin?

  60. Chris December 23rd, 2014 12:00 pm


    I’m not sure what is “safe”, but as you’ve clearly demonstrated it’s many different factors. It’s very complex and technical aspects that are beyond my practical engineering skills to understand. But something like “uphill release” is a factor with AT bindings and typically not a consideration for an alpine binding, so there are other issues to consider. I’m just trying to distill this down to useful information when deciding to make a purchase or possibly influence that decision. Probably not entirely possible at this time.

    Thanks for all your thorough information and sharing of this complicated topic, nice work!

  61. JR December 23rd, 2014 4:48 pm

    It would be lovely to see the results a large randomized control trial constituting 10,000 skiers each in telemark, tech binding, alpine binding, perhaps the “knee” binding that claims to have such significant safety release features, and a group strapped rigidly to skis without release (for all we know this could be the safest group of the bunch!). Send all 50,000 skiers into a series of horrible high speed crashes, and we’d finally have the objective injury data we crave when making purchasing decisions! If done correctly, you may be able to do subgroup analysis varying DIN setting with weight.

    Yes, this clinical trial may have some issues getting the necessary research board approval – but how much more ethical is it for all of us to use these exact same setups in multiple daily crashes without any objective evidence the decisions we make (and spend hundreds of dollars on) ? How ethical is that?

  62. Lou Dawson 2 December 23rd, 2014 6:00 pm

    LOL, JR, economists, statisticians and engineers can get that same information in other ways, it’s just a matter of money and time to do the studies.

    Main thing is to cut through the mythology. Jason and Rick are helping with that. I mean, how many of you knew that tech bindings might be better for your knees than alpine bindings?

  63. jbo December 23rd, 2014 10:14 pm

    See – There are some designs with swappable forks that change release values, e.g. Plum 135 vs 145, Dynafit LTR titanium vs steel forks. Seems like there is an aftermarket opportunity as well. B&D has a lighter lateral spring for the Radicals, but I don’t think Bill has upgraded to race bindings yet.

    Charlie – I had a similar line of thinking re: heel testing. However there is no algorithm to stitch together heel + toe + boot data into meaningful torques on your leg. Instead I’ve been testing various combos whenever I can and recording the results, in view of the bigger picture above.

    Lou – I bet your speculation about the Vipec is correct, can’t wait to find out.

    Rick – Thanks for the references. Looking forward to reporting on all our other findings.

    JR – Don’t forget about low speed crashes, I’ve broken more bones with those.

  64. VT skier December 24th, 2014 8:35 am

    One other point, with ski shops filling up with more AT boots with inserts just waiting for a pin tech binding.
    User Error, which caught up to me last winter.
    After a warm Tram ride, I casually stepped into my pin tech binding (Verticals) , banged the ski on the snow a bit, then went carving down an icy groomer at the resort.
    At Mach schnell, I had a pre-release, that banged me down so hard on the piste, it ripped a chunk out of my helmet.
    Luckliy when I fell I didn’t tumble into the trees lining this run.
    The culprit? Probably ice that had formed in the warm “cups” in the inserts of my Rush AT boots as I stepped off the Tram.
    Now I very methodically step into the toepiece, then pull the lever into tour mode, rock my ski back and forth a few times, before I step down into the heels. Lastly, I flick the toepiece back into ski mode.
    How many new users of pintech boots/bindings will know about this “ice-in-the-cups” issue?
    They will just blame the pintech binding when they get a pre-release.

  65. Lou Dawson 2 December 24th, 2014 9:00 am

    Calling all, Rick and Jason gave me some video footie I whipped up in my vid edit software for a YouTube treat. Embedded at the beginning of post above, or check it in YouTube at


  66. Lou Dawson 2 December 24th, 2014 9:24 am

    VT, icing is the cause of most pre-releases of tech bindings, in my opinion, and you’ll see more of this as people used to alpine bindings switch to tech without learning how to use them correctly. It’s not just ice in the boot toe sockets, but also in the pocket under the toe wings. Double trouble. It’s actually kind of odd that the TUV testing for ISO didn’t catch this on the several tech bindings that received certification as it’s a huge problem, but then, the ISO standard most certainly was not designed for tech bindings! Lou

  67. See December 24th, 2014 9:43 am

    I’m not second-guessing VT or Lou here, but “carving down an icy groomer at the resort… (a)t Mach schnell” are the sort of conditions that can be problematic for tech bindings even without boot or binding icing (as always— in my opinion/experience).

  68. Lou Dawson 2 December 24th, 2014 10:09 am

    Over the years, I’ve seen quite a few racers having problems with the same conditions (grin).

  69. UpSki Kevin December 24th, 2014 11:33 am

    Really interesting stuff! Especially that my 2010 ‘skiers thumb’ injury is #3 most likely on the list. (yes, caused by a ‘pre-release’… the binding pre-released off of the ski!).

  70. VT skier December 24th, 2014 11:38 am

    Lou, I also flick the toe piece open and closed a few times, holding the ski upside down, to remove ANY ice/snow I see in the pocket under the toe wings of my Verticals.

    Buyer education will be important in the ski shop, when people first purchase these tech bindings, appearing now at ski retailers everywhere.

    @See, Mach schell on my Nunataqs, isn’t Mach schnell as on my Mantras 😉

  71. See December 24th, 2014 12:01 pm

    Yeah, that’s the problem.

  72. VT skier December 24th, 2014 12:30 pm

    I meant Mach schnell on my Nunataqs with Verticals is pretty slow as compared to how fast I ski on my Alpine 186 Mantras.
    Now that I am more methodical with how to avoid pintech icing issues I have had no further pre-releases..On hard icy snow I dial the speed back quite a bit too.

  73. Rick Howell December 24th, 2014 1:01 pm

    Several different pintech bindings needed to be cycled into and out-of the locked-touring mode at the toe in order to fully-seat the pins into the dimples. I found that if I failed to do this (again, with several — but not all) before conducting a release test, it became one of the largest sources of variability in quantifying the resultant torques on the leg. Typically, release was ~20% lower than in the fully-seated position. All of this was without any snow-pack or ice in the dimples.

  74. See December 24th, 2014 1:48 pm

    VT, understood.

    Rick- care to open the can of worms that is the effect of # of toe lever clicks on release torques?

  75. Rick Howell December 24th, 2014 1:56 pm

    @See — Variation in peak release stabilized to within ~ +/-5% after ~2 lever clicks on the brands that did not fully-seat upon step-in.

  76. See December 24th, 2014 3:56 pm

    Thanks Rick. That’s really interesting and (if the toes that required cycling don’t eventually break in) also a bit troubling.

    Re. my question, however; I’ll take your answer as a “no.” (Just kidding). I was referring to the ill-advised practice of “locking the toes” in an attempt to mitigate prerelease issues. (I’ve heard that some misguided individuals believe that the ski/tour lever can be used to adjust release torque beyond simply locked or unlocked).

    Best wishes to all.

  77. jbo December 24th, 2014 3:57 pm

    Since there aren’t rigorous standards defining the bootbinding interface, there are often issues with sole shapes interfering with proper binding operation. This can manifest as difficult entry, exit, or release. With certain pin heights and sole rockers, lugs can even hug the ski. Altering soles and other workarounds are common. It’s hard to point fingers at just the binding or just the boot in these cases, as they may work fine with other boots or bindings, respectively.

  78. Bruno Schull December 25th, 2014 9:44 am

    Hi. Thanks for the information. Very interesting. I think I don’t understand something fundamental to your work. In the beginning of your post your write: “The perfect binding would have a flat line in the graph, meaning it releases at the same tibia torque regardless of where the lateral force is applied….But as you can see, in the real world there are peaks and valleys in the envelopes.” My question is, “Why are there peaks and valleys in the envelopes?” or “Why does changing the position of the applied force along the ski change the torque at release? Just based on simple physics of torque, levers, and so on, I understand that changing the position of the applied force along the ski changes how much applied force is necessary to release the binding; I guess that as you move toward the tip or tail of ski, you increase the length of the lever arm, and less force is required to get the binding to release. But why does changing the position of the applied force along the ski actually change how much force is required to get the binding to release? I would expect that a binding would always release at close to the same force in most circumstances. How would the binding “know” or “sense” where the force was applied? Deformation of the ski? Different lateral and vertical components of the forces on the bindings, which change how the springs are flexed? Different friction forces produced by different angles? Can you correct my thinking, or provide any insight? Thanks again.

  79. Rick Howell December 25th, 2014 10:19 am

    @ Bruno,
    Thank you for your good question.

    The tibia-torque envelopes in graphs 1 & 3 show that when a lateral force is applied directly next to the binding’s pivot-point that’s ford about a vertical-virtual-axis, torque about the leg approaches infinity. This is because, in the case of pin tech binding’s, the ski cannot release laterally ‘through’ the posts of the pins: however, the pins are located a difinitive distance away from the 2nd virtual-pivot that’ formed by the long axis of the tibia — therefore, the nearly infinite-force that’s attempting to be applied to cause release (applied directly-laterally next to the pins) acts over the lever-arm that’s formed back to the tibial-axis … To generate nearly infinite torque about the tibia. In the torque-envelopes, the torque that’s formed about the tibia (for any given applied force along the length of the ski) is represented by the magnitude of torque-about-the-tibia AT THE GIVEN POINT ALONG THE LENGTH OF THE SKI.

    In this way, one can also see that when a lateral force is applied to the ski directly under the tibia, the torque-about-the-tibia is zero.

    In graph #2 (an ‘applied-force’ envelope), here you see the effect of what you are envisioning. Here, as the distance from the applied force to the binding’s natural pivot shortens, the magnitude of the applied force must increase.

    As for the valgus-torque envelopes (overlayed on graph 3), the effective lever-arm spans from the snow-surface to the hip. If there is no lateral release at the heel (ordinary alpine bindings), then valgus-torque is maximal. Lateral heel release interrupts the kinematic pathway between the snow and hip to become the weakest link in the chain, rather than the ACL being the weakest link in the chain in the absence of lateral heel release.

    The graphs show all of these biomechanical interactions, experimentally, via actual measurements (without any ‘theory’)

  80. Rick Howell December 25th, 2014 3:52 pm

    @ Bruno,

    Once again, thank you for your question. Pls pardon my typos while trying to respond too quickly on the fly by cell phone.

    Another way to envision the torque-envelopes (graphs 1 & 3) is to consider them with only the tibia fracture limit being plotted. In this way, tibia-torque is always constant at 11.3 daNm — kind of like 11.3 ‘DIN’ — for an average U.S. male weighing ~170 pounds. The tibia fracture limit, in terms of torque, is always the same no matter how long the ski is — or where on the ski the applied lateral force enters the ski. The tibia fracture torque limit is always a contant — its a flat line when plotted on a TORQUE envelope.

    Now look at the tibia fracture limit that’s plotted on graph #2. Graph 2 shows the magnitude of the applied lateral FORCE at all points along the length of a ski (a ski that’s fixed to the distal end of the tibia, bolted to the tibia without a binding) necessary to take the torque-about-the-long-axis of the tibia to 11.3 daNm.

    A binding is a force-imparting mechanism that acts over the effective lever-arm supplied by the binding’s pivot-point — utilizing the boot as the coupling between the force-imparting mechanism & the related-pivot. In concert, the binding supplies a fixed amount of ‘resistive’ torque.

    If the pivot formed by a given binding’s design (in conjunction with the boot) is not aligned with the long axis of the tibia, this ‘off-set’ will cause the ‘bulges’ that are shown in the above envelopes.

    The beauty of reporting binding release behavior in this way is that the analysis is oriented around the biomechanics of the tibia.

  81. Neil December 25th, 2014 5:43 pm

    Richard, is there any analysis of fibula fractures as well? Just of interest as a friend’s Dynafit bindings failed to smoothly release on some sticky snow resulting in a helicopter medivac from a glacier (in NZ) a couple of months ago. Conditions were a little unusual as we were ski touring with 30kg packs between huts.

  82. Rick Howell December 25th, 2014 6:51 pm

    @ Neil — Yes, there are 2 outstanding research papers on fibula fractures in skiing. Both have the same conclusion — that the typical fibula fracture is caused by the outside of the lower leg having impact with an object or ‘firm snow’ during a fall.

  83. Rick Howell December 25th, 2014 6:58 pm

    p.s. — Fractures of the fibula are rare, with a prevalence of less that 1% of all skiing injuries … and this level of prevalence has remained steady for decades.

  84. jbo December 26th, 2014 12:56 am

    Neil / Rick – My fibula break was caused by rock, outside lower leg. Non-union too, probably another 1% subset. Alpine bindings + the opposite of skimo race skis. This is just noise statistically.

  85. Rick Howell December 26th, 2014 3:34 am

    That’s correct, fibula fractures are not binding-related.

  86. Rick Howell December 26th, 2014 7:25 am

    @ Neil & Jason Borro (jbo) — To close-out the fibula discussion relative to bindings — the biomechanical REASON WHY fibula fractures are unrelated to bindings is because the kinematics of the unique load (force, torque, or moment) that causes fibula fracture does not pass through the binding. The binding has no way to ‘read’ or ‘react’ to a load that impacts the outside of the lower-leg … nor should a binding read or react to such loads, because fibula fractures are epidemiological anomalies ( < 1% of all skiing injuries ). If a binding were designed to deal with these kinds of anomalies, unwanted adverse side-effects (such as: pre-release; durability; excess weight) would most likely arise.

  87. Bruno Schull December 26th, 2014 2:01 pm

    Rick, thank you very much for your answers. I printed out the graph, read over the posts and your answers, and I think they make sense now. The key for me was realizing that the vertical axis in the center of graphs represents the tibia axis, and that the increments are measured forward and back from that axis. I could then see why there are blind spots for different kinds of bindings in different positions. You can not make a typical tech binding release by pushing directly against the side of the pins at the toe (about + 20 cm), and you can not make a typical alpine binding release by pushing directly against the side of heel (about – 10). Once I realized that these blind spots exist, I could see why changing the position of applied force along the ski would produce different forces on the leg. Is that right?

    I have a follow up question. On graph number four, with the red and gray overlays, it makes sense to me that the alpine binding produces high valgus moment between approximately 5 and 20 behind the tibia axis. It also makes sense that the tech binding produces high tibia torque between approximately 10 and 30 centimeters ahead of the tibia axis, for the reasons described above. But what about the valgus moment for the tech binding ahead of the tibia axis? This appears to increase steeply between 10 and 30 centimeters ahead of the tibia axis. Wouldn’t that also be a potential zone for an ACL injury? In graph number 3 you showed the simulated ACL strain for applied forced behind the tibia axis. Would the ACL strain still be below the rupture limit if you showed the values from ahead of the tibia axis? I’m probably still missing something basic about the graphs.

    Last, I understand that you are a binding engineer, working on a binding with both toe and heel lateral release, that also keeps the ski firmly attached to your foot when you need it to be. If you make the binding hold your foot firmly, I imagine you also increase the risk of injury. How close are the forces involved in holding the ski on your foot, and preventing injury? Without revealing any secrets of your design, can you comment at all on how you accommodate these opposed design constraints?

    Again, many thanks for your work, and generous replies. It’s very interesting to learn about a complex problem.


  88. Rick Howell December 26th, 2014 2:32 pm

    @ Bruno —

    1— Regarding your 1st question:

    ACL rupture occurs when a discrete combination of valgus-moments and tibia-torques are combined. Please see:

    [ SHIN, C. S., A. M. CHAUDHARI, and T. P. ANDRIACCHI; Valgus Plus Internal Rotation Moments Increase Anterior Cruciate Ligament Strain More Than Either Alone.; Med. Sci. Sports Exerc., Vol. 43, No. 8, pp. 1484–1491, 2011 ];


    [ The Effect of Isolated Valgus Moments on ACL Strain During Single-Leg Landing: A Simulation Study. Choongsoo S. Shin (a,????), Ajit M. Chaudhari (b), Thomas P. Andriacchi (a,c);

    a Biomechanical Engineering Group, Department of Mechanical Engineering, Stanford University, Stanford, CA 94305-4038, USA

    b Department of Orthopaedics, Ohio State University, Columbus, OH, USA

    c Department of Orthopaedic Surgery, Stanford University, Stanford, CA, USA ]

    In my experimental simulations utilizing extrapolations of Andriacchi’s ACL rupture envelope (see the 1st-paper referenced, above — noting that Professor Andriacchi also suggests to not “over-apply his data” … ) the essential combination of internal valgus moments ( ~ torque) and internal tibia torque cause the ACL to exceed the rupture limit when sufficient abduction-force is applied to the medial edge of the ski ONLY between -5 cm and -20 cm aft of the projected axis of the tibia.

    All combinations of valgus and tibia torque that result from lateral (abduction) forces being applied to the medial edge of the ski FORWARD of the projected axis of the tibia cause internal rotation of the femur (valgus) and external rotation of the tibia: these two DIRECTIONS unwind the key anteromedial bundle of the ACL: lateral loading of the ski FORWARD of the tibial-axis does not generate strain across the ACL in sufficient magnitude to cause rupture.

    2— Regarding your second question:

    I’ve utilized the new engineering science of ‘Axiomatic Design’ to cause functional decoupling between release and retention. In this way, release is treated as a separate system from retention. This is why we cannot seem to produce pre-release even with chart-settings. This is a 1st in ski-binding design (and it’s protected by IP). You can see some of this engineering applied to my ski bindings in the website: []. With this approach, we can ski with tibia-friendly, ACL-friendly and anti-pre-release confidence.

  89. Bruno Schull December 26th, 2014 11:48 pm

    Thanks again Rick. A please to exchange ideas with someone who REALLY knows his subject. I will follow your binding development. As a over-forty year-old with several knee operations and poor knee connective tissue, I am intrigued by the idea of a knee-friendly binding. All the best, and keep up the great work. Bruno.

  90. Lou Dawson 2 December 27th, 2014 5:46 am

    Whew, what a thread! How ironic. In classic form the tech binding is shown to at least provide a modicum of knee protection, can’t get ISO certified, hasn’t changed much in 30 years, and now we’re getting “improved” tech bindings that don’t release at the heel while still claiming they’re “safer.” As Fritz told me about a year ago “things are going to get interesting.” And now we’ve got the Marker Kingpin that _does_ release sideways at the heel, only different… and does get ISO certified, while the Vipec looms out there with side release at the toe instead of the heel, perhaps better retention, perhaps not, no way to really tell. Oh, and the Beast offerings from Dynafit keep the lateral heel release only with perhaps better retention. On top of all that, we’ve got the Trab binding and boot here to really keep us overwhelmed with things to do. If the alpine binding market was this complicated, they’d probably make a law…

  91. Lou Dawson 2 December 27th, 2014 6:00 am

    I’d also add that the elephant in the room is, can you ski classic tech bindings unlocked, at recommended “DIN” chart release value for your size, age etc.? If so you are perhaps indeed getting some protection for knee torque injuries, but to prevent unintended release many people either ski the bindings locked, or else at higher release values. For example, see above testing that shows that a tech binding had overall higher release values than the printed numbers would imply, meaning that in real life perhaps you’ve been thinking you’ve adjusted your bindings to the recommended torque levels, but you’re actually skiing them at a higher setting (again, the reason why testing with ski shop binding tools is important.)

    Unintended binding release is incredibly dangerous, in many ways more dangerous to your overall well being than blown knees or broken tibias. What is more, falls CAUSED BY pre-release are known to result in leg injuries to the leg that’s still attached to a ski. I’ve had that happen, and I’ll bet a few other folks here can testify.

    Thus, Bruno and all, while we do want to protect our lower legs and knees, good skiers who don’t fall much should be keeping their priorities straight. Staying in your bindings is far and above the most important aspect of binding safety performance, and this testing is not about that.

    I’d imagine Rick has some pretty good tests to evaluate binding retention. Perhaps they’ll be applied to various tech bindings some day.


  92. See December 27th, 2014 8:22 am

    In retrospect, I probably should have used some sort of emoticon in an earlier comment where I called locking the toes “ill-advised.” (Lou, edit as you see fit.) To be clear, I lock the toes on my Verticals in no fall situations.

  93. See December 27th, 2014 8:28 am

    Make that “some no fall situations.”

  94. wyomingowen December 27th, 2014 9:52 am

    Lou, exactly my experience in a distal fibula fracture 5 yrs ago. Operator error, jumped in low tech bindings without clearing snow. Left ski popped off 3 turns in and injury occurred to right leg with ski attached as I punched deeper into snow pack. Now always whenever a boot pack is required I use the tooth on a voile strap to ensure toe is clear of snow/ice. A memorable ski back to the car for sure….can you say, falling leaf

  95. ph December 31st, 2014 12:40 am

    Great info and would love to see the Vipec and Kingpin tested!

    In fact if it worked to use Vipec toe and Kingpin heel together to get a binding setup with front and back lateral release that would be useful data.

    But I’m not sure a Vipec toe would react well to a lateral heel release.

  96. Rick Howell December 31st, 2014 1:24 am

    @ ph — $5k / sample; next 5 days are available.

  97. Alan December 31st, 2014 7:33 am

    Hi, I’d like to hear what your experiences are with the ATK race touring and freeride 12 bindings, also: how do they compare to the new g3s. Could this be, say with Dynafit Denali skies, a reliable go anywhere and do anything set-up?
    Regards, Alan

  98. Kristian December 31st, 2014 8:10 am

    When skiing powder, undergrowth sometimes catches and flips up the front pointing lever from skiing mode to full locked touring mode. The skier is unaware that they are locked in with no binding release possible.

    Surprised that this is still possible.

    On a related note. Last year I shed my quiver of boots and skis and now ski backcountry and resort double blacks with Maestrale GS Boots and Dynafit STs. Liberating like bunny hopping a light xc mtn bike. Am I am idiot? (Pushing light gear too hard? I ski light precise controlled.)

  99. Lou Dawson 2 December 31st, 2014 8:37 am

    Kristian, my take is that if you’re not getting accidental releases (pre release) you are way ahead of the game on any binding, provided you’re the type of skier who seldom falls. Nonetheless, main thing is if you _can_ ski the binding unlocked, at reasonable settings, so you might get at least a smidge of leg bone and knee protection out of the deal. Lou

  100. ph January 4th, 2015 1:17 pm

    @ Rick – Offer appreciated, although I’d look for another 99 forum participants to contribute too.

    Anyone have any insight about the choice of the ISO 9462 test zone, outside of + or – 45 cm from tibia axis?
    Is it designed to be longer than the typical shortest ski people would use, with some statistics that any likely load is likely to come from the ski ends?
    Or make it easier/more practical for standard alpine bindings to meet certification?

  101. Rick Howell January 4th, 2015 2:46 pm

    @ ph: The concept of biomechanically measuring a full-envelope is that it averts a large amount of the guesswork of ‘statistics’. Generally, the term ‘statistics’, when utilized in ski-injury research, means ‘epidemiology’ — the investigation of injuries and related factors IN THE FIELD. By performing biomechanical testing of a full release envelope ALL possible injury mechanisms are tested — without relying on ‘statistics’. Further, I in my proprietary tests, I’ve expanded the test protocol of ISO 9462 Method B by measuring BETWEEN the -45cm to +45cm zone in order to generate test-data for skis that are shorter than this zone; AND I’m not only measuring tibia torque, but ALSO uniquely measuring Valgus-torque. Measurements within the ISO 9462 Method B zone ( less than -45cm and more than +45cm) provides us with biomechanical data about how a binding will interact with tibia-integrity, AND how well a binding performs relative to the accepted minimum international ‘safety’ standard. Measurements inside of the -45cm to +45cm zone AND the measurement of valgus-torque (neither of which anyone else measures) uniquely tells us about a binding’s interaction with ACL and MCL integrity AND tells us about the biomechanical interaction of a binding on a short ski. Lastly, again, measuring a full envelope (as I uniquely do) eliminates the guesswork of ‘statistics’: there are no ‘statistics’ involved in my biomechanical tests.

    Performing full-envelope release tests provides us a full quiver of biomechanical information about how a binding interacts with the human tibia AND the ACL, independently of ‘statistics’.

  102. Stefano January 5th, 2015 2:28 am

    As Murphy said ” Is better to know the true with lot of imprecision, that insisting to search for the the perfection, knowing nothing…”

    All this very interesting “static” test give us the base to argue that:

    DYNAMIC release is another BAD story:

    1. somethink that release under slowly load do not under very fast ones…

    2. F=m*a… is here forgotten since there is a “oil piston” that generate forces so torque…

    3. ALL the Pin Bindigs (except to the ones installed onto my Natural Walking Plate Spars) are subjected to ski bending so to BOOT COMPRESSION BETWEEN THE BINDINGS (2-4mm of play on the pin is not enough to avoid collision and locking that happen in all the 1 1,5Kg skis…)

    So if you wanna be light be prepared to ski well….

    What is very dangerous is that Pin “moda” is flloding Freerider world, so FAT skis, high Speed, heavy load for jumps, bad snowpack, and “In piste skking”…

    Put this with “all type of Skiers…” with “any kind of old Skimo Boots…” and this become a clearely bad way to go in the future…


  103. Rick Howell January 5th, 2015 5:34 am

    @ Stefano: I’ll be glad to host you here at my humble lab in Stowe, Vermont USA at any time. 🙂

  104. Chard January 10th, 2015 10:05 am

    I had a hard time finding my ACL tear on the graphs as it was a forward lean hyperextension where the heel piece failed to release. I was basically cartwheeling and one of my tips caught as my body continued to go forward, so all of the pressure was right at the tip. This seems to be more of a tibia fx issue according to your graphs, but in my situation it was a clean (and painless) full ACL tear. Is this a less common ACL MOI? I was on Radicals and in BD Quadrants, which I believe may have had some insert problems. I was so spooked after this that I now have a “beefy” resort alpine set-up and a BC tech set-up, though for typical ACL injuries this might not improve my chances…

  105. Lou Dawson 2 January 10th, 2015 10:41 am

    Chard, the upwards/forward release on tech bindings is very easy to check, but on most models it does lack the same elasticity as good alpine bindings, so there is sometimes a tendency to dial it up too high. Did you ever have the release value of the bindings checked, and did you carefully set it, or did you just “dial it up?”

    I ask because setting your release values too high (above chart) on either a resort or backcountry binding system is almost a guaranteed injury in some types of falls.

  106. Rick Howell January 10th, 2015 11:00 am

    @ Lou,

    Of course, as we all know — based upon the myriad of long-standing published, peer-reviewed, scientifically-correct research papers that have been in the public domain for over 20 years on the interrelationship between ski-binding release settings and ACL-injuries from a biomechanical AND from an epidemiological perspective — ski-binding release settings (in an ‘ordinary’ 2-mode binding) have NO correlation with ACL-injuries. We could have our ‘ordinary’-binding settings set at one-DIN (1.0 DIN) (( that’s a light children’s setting )) and as adults, we could easily sustain a skiing ACL-injury.

    @ Chard,

    Yes, you are right, Chard — that’s another ‘injury-mechanism’ that’s not being modeled in my test-protocol. That injury mechanism ‘far-forward-twisting with hyperextension’ is though to have a prevalence of ~1% to 2% of all skiing-ACL-injuries.

    Another injury mechanism, pure backward loading (called BIAD — which is an acronym for Boot Induced Anterior Drawer), is thought to have a prevalence of ~8% of all skiing-ACL injuries.

    The main injury mechanisms are ‘valgus-dominant’. They are called Phantom Foot (PF) and Slip-Catch (SC): they represent ~70 to 80% of all skiing-ACL injuries. The difference between PF & SC, biomechanically, is knee flexion angle: FP is thought to be associated with knee flexion that’s >90°, while SC is thought to be <90°. My testing that's published here simulates only PF and SC injury mechanisms that are thought to have a prevalence of ~70 to 80% of all skiing ACL-injuries.

  107. Lou Dawson 2 January 10th, 2015 12:53 pm

    Rick, sure, I could have written it as “I ask because setting your release values too high (above chart) on either a resort or backcountry binding system is almost a guaranteed injury in some types of falls. Also, note that some injuries are inevitable as bindings can’t protect you from everything.”

  108. Rick Howell January 10th, 2015 1:01 pm

    @ Lou, ‘Catch-all disclaimers’ on ski-binding and/or their settings ignore the #1 and #2 injury problems that can be mitigated in skiing: ACL and MCL injuries and ignore the simple fact that ski-bindings with lateral heel release that are properly tuned can significantly reduce ACL and MCL injuries.

  109. Lynsey Gammon January 16th, 2015 9:06 pm

    I’m your tester in the vipec department. I tore my ACL in vipecs in a slow forward fall w slight twisting. I purchased the bindings to hopefully prevent an injury like this (my second). Sadly, it wasn’t to be. I wish more accurate information would have been distributed by Fritschi as to the reality of the lateral toe release and the lack of lateral heel release. While I didn’t break my tibia (thank goodness), an ACL is incredibly frustrating…

  110. Jim Milstein January 16th, 2015 9:33 pm

    Sorry to hear of your injury, Lynsey.

    It would be interesting to know at what values your release was set and how those values were determined. Any other information you’d care to offer about the circumstances of the accident would be welcome. As another skier using Vipecs, I have a vital interest in their safety.

  111. Lynsey Gammon January 16th, 2015 9:45 pm

    Hi Jim,

    My release values were set at a DIN equivalent 6. Black Diamond in Salt Lake determined my release values and mounted my skis for me. I am a 5’8″, 125 pound skier, but fairly aggressive/expert by their standards. I’m considering selling the Vipecs right now, as I’m too freaked out. However, my husband has the same bindings set at a release of 10, and came out twice (which was a good thing!)

    My fall was kind of the typical ACL. I was skiing heavier snow, hit a old skier’s track, my tip dove, and I kept going forward. It’s hard for me to say now if I was twisting, but either way, the binding did not release (neither heel nor toe). Sadly, (or luckily) I was on the last day of a 7 day backcoutnry trip in the Selkirks. But this also meant I had to skin out 1500 vertical feet with no ACL.

    All is well now, I had surgery in May, and am ready for skiing this winter, if I can ever get over the mind games of the vipec…

  112. Jim Milstein January 16th, 2015 10:39 pm


    I suppose you could go hybrid, keeping the Vipec toe and using a standard tech heel with lateral release. Lateral release fore and aft!

    My Vipecs are adjusted to DIN 5 and have never released, but they haven’t needed to. I’ve been bouncing around on logs a lot this season due to low snowpack in southern CO. So far, so good. I weigh 150 lbs.

  113. Lou Dawson 2 January 16th, 2015 11:45 pm

    Hi Lynsey, really sorry to hear about that. Thanks so much for sharing about your injury, it’s important that folks know that people are out there getting hurt on ski bindings, and there is thus room for improvement. Sometimes I feel like the whole industry, consumers and manufacturers alike, are in a state of denial about this stuff.

    If you’re not happy with the bindings my advice would be to sell them and use something else. But I’d also caution you to realize that people blow out their knees while hiking, e.g., ski bindings can never protect 100%, and all ski bindings provide more or less protection depending on the type of fall and forces involved. It’s true that Vipec “releases sideways at the toe” and that makes a lot of skiers want it, but on the other hand it doesn’t release sideways at the heel, so it’s similar to most alpine bindings in that way. And the fact is, the big problem in alpine bindings these days is people are still blowing out knees and not getting the knee protection they should in my opinion be getting. So sadly, the performance you got with your Vipecs could be no different than what you’d get with the best alpine binding out there.

    But again, it’s worth repeating that no ski binding can protect you 100%. And as you ski better and with more energy, you many need higher setting as any ski binding is a COMPROMISE BETWEEN RELEASE AND RETENTION. In other words, again, no binding can protect 100% all the time.

    When you do decide on a binding, I’d suggest you play around with using lower release values, and be sure to have the binding torque tested at the retailer to make sure the value it is set at actually matches what it’s supposed to be. You can set a binding according to the numbers printed on the housing and it can be off quite a bit, for example a 6 could actually be a 7, or a 5.

    If you wanted to, it wouldn’t be a bad idea to have your Vipecs torque tested so you have a baseline idea of what setting you were truly skiing with.

    Another thing you can do is set upward/forward release differently than side/lateral, depending on your style of skiing. For example, I’ve found for myself that I can set my tech binding lateral release quite low, around 6, and not come out in normal skiing, but I like having the upward release set at 7 or I pop a heel out occasionally while absorbing transitions. The idea being to set the binding as low as practically possible, while remembering that accidental release is a serious safety issue as well.

  114. Rick Howell January 17th, 2015 9:05 am

    Hi Lynsey,
    Actually, if your tip dove-in and you continued forward … this means that the loading condition was not forward (not pure-forward; and/or not forward-twisting — yes, we don’t know about the ‘twisting’ part, and we’ll probably never know about the twisting-part). This type of fall-mechanism is what’s called ‘BIAD’ (Boot Induced Anterior Drawer). The ski was pulled (sort-of) ‘under’ you. This is equal — in terms of the ‘engineering-load’ — to slamming the tail of your ski while landing a jump. This type of injury-mechanism (tip diving, while you continue forward) forces the high-back of the boot to push the proximal end of the tibia, forward … while the inertia of your upper body (and femur) exert resistive (equal magnitude, opposite direction) momentum. The weakest link in this chain is the ACL unless you have UPWARD TOE release. Based on the good-scientifically-correct epidemiological research studies (the Sugarbush Studies; and independently, the studies by the Medicines de Montage) — the BIAD injury mechanism is thought to be associated with ~8% of all skiing-ACL injuries. Release settings (high or low) will have zero effect / zero-intervention / with this type of BIAD loading condition unless you had an adjustable vertical toe release, which you don’t. Only the Geze SE3 (sold between 1979 and 1985 — perhaps the world’s most exotic ski binding) had adjustable vertical toe release that was independent of the lateral toe release. Lateral heel release has no effect on BIAD ACL-injury producing loads. ( Lateral heel release addresses the dominant type of skiing-ACL injury: Valgus-dominant loading. )

    Jim (and Lou) —
    We’ve already referenced major (‘good’) studies that show zero correlation between release settings and ACL injuries. Having your ‘ordinary’ (lateral toe release, forward heel release) bindings tested for release will have zero effect on ACL-injuries. Having your ‘ordinary’ (lateral toe release, forward heel release) bindings tested for release DOES have a direct material effect (high, positive correlation) on tibia-friendly skiing.

    The above graphs in Jason’s article show exactly why release settings (with ‘ordinary’ bindings having only lateral toe release and forward heel release) have no biomechanical effect with ACL-integrity; AND the above graphs also show why release settings with pintech bindings have little biomechanical effect on tibia-integrity. The DESIGNS of these bindings (their unique ‘kinematics’) override any effect on ACL-integrity — or, respectively tibia-integrity — (‘ordinary’ alpine; or respectively, pintech) regardless of release settings. The unique DESIGN of a given binding’s kinematics over-rides the effect of release settings (high or low).

    Rick Howell
    Howell Ski Bindings
    Stowe, Vermont

  115. Lou Dawson 2 January 17th, 2015 9:32 am

    Rick, thanks, keep it coming. I have little faith in most bindings to yield much if any protection for the knees, but somewhere beyond faith lies the theory that at least the settings should be set as low as possible, and perhaps another part of the fall will effectuate a binding release before the ACL damaging part of the motion. I think I’m probably just too nice. I’ll mend my ways. I’ve injured knee ligaments a number of times on both alpine and touring bindings, including once on telemark bindings. If I can remember down the line, I’ll pretty much take the position that you’d better not be falling if you want to preserve your knees — the binding makers are not going to help, they spend all their money making and marketing helmets, and ignoring knees. Lou

  116. Jim Milstein January 17th, 2015 9:53 am

    Well, Lou, that actually is my principal strategy to remain unbroken: Do Not Fall. The most important technical skill in skiing is to remain standing. Everything else follows from that.

    Gotta go (skiing!)

  117. Rick Howell January 17th, 2015 10:03 am

    The science behind this issue points to two sources of information that can enlighten us.

    1— The Sugarbush Study showed that the ACL-injured-skier-group had the same release settings as the control group of skiers. This means that release settings have no epidemiological-correlation on skiing ACL-injuries.

    2— Jason’s article (above) shows that when a ski is loaded in all possible valgus-dominant conditions, some loads — such as loads applied to the front 3rd of the ski and the aft 3rd of the ski — precipitate a tibia fracture. However, when the middle 3rd of the ski is loaded, an ACL rupture is precipitated. These loading conditions are independent. When the tip or tail are loaded, a tibia-fracture can result. When the middle third of the ski is loaded, an ACL-rupture can result. The type of injury is dependent upon the type of loading.

    There are 2 binding companies that are directing resources toward providing ACL-friendly skiing: both have lateral heel release: lateral heel release addresses loads that enter the middle-3rd of the ski.

    I think we might finally be at the point where we can start to rely upon engineering science to address the skiing-ACL situation.

  118. Lou Dawson 2 January 17th, 2015 10:03 am

    Problem is, when people ask for advice about preventing injury, it sounds callous to say “don’t fall.” But it’s true. No matter how good your helmet, your bindings, your knee pads, your airbag backpack or your first aid kit, prevention does come first. Easy to forget. Lou

  119. Frame January 17th, 2015 11:50 am

    Very interesting read all this. In my youth, all skiing inbounds, I didn’t consider it a proper day skiing unless I had wiped out at least once. Age, listening to conversations like this, kids and a broken pelvis all make one have a wry smile and shake of the head at ones self.
    Rick I appreciate all the effort you have put into the comments section and writing in such a way that I (the layman) understand most of what you say. Jason, thanks for the original article.

  120. Lou Dawson 2 January 17th, 2015 11:24 pm

    It may sound factitious and is stating the obvious, but not falling is the best way to prevent injury. What makes this a real concept is good skiers who don’t get crazy can go through a whole season, a hundred days or more, with just a handful of falls or even none. If you live the ski life, on through middle age, it’s essential to develop this style otherwise you’ll spend too much time and money on injuries.

    The problem with this is if you make not falling your number one priority, and you’re not a great skier, _trying_ not to fall will lock up your body, you won’t be fluid and relaxed, and you’ll fall more.

    It’s possible to be just an average or intermediate skier to ski relaxed, but you have to work on that concept and adjust your expectations. For example, you might sideslip weird situations a bit more than your friends who are better skiers, or you might throw in a traverse and kickturn now and then.

    It’s also important for any skier to develop habits of recognition that prevent injuries from situations such as road transitions, somewhat hidden terrain features, and even how you stop during a run when other people are around (if they look scared and start moving when you show up, you’re doing it wrong .)

    Another thing about all this. If you’re serious about preventing injury while skiing, no alcohol during ski day, don’t ski when tired, and beware back-to-back ski days with no recovery time. These hut trips that pack multiple huge days back-to-back concern me. Top athletes can handle that, but many people would be much better off with numerous rest days.


  121. Kristian January 18th, 2015 5:51 am

    Best skiing advice ever.

  122. Rick Howell January 18th, 2015 7:59 am

    Yes, Lou, there’s also a considerable amount of published epidemiological research on “not falling”. Falls contribute 80% of all skiing injuries. ‘Ability’ does not correlate to falls, but experience (number of days skied in a lifetime) does correlate to falls. Inversely, and interestingly, falls are not linked to time of day — but to number of hours skied in a given day.

    And yes, we all know that no binding can “prevent” injury.

    But this thread is about what happens when you do fall — and what happens, then, with differently pintech binding designs.

    Here we can see that in regard to tibia-fractures, the most basic of Isaac Newton’s equations — Torque equals force times distance — is the key factor in how a given binding design can respond to a potential-(torsional)-tibia-injury-producing-load (“distance’ = the length of the effective lever arm). The main point is that the above equation does not say, “torque equals 3-times force times distance. But many people, in fact, place far too much emphasis upon and focus way too much belief that the binding’s force imparting mechanism (the release setting) plays a more significant role in the outcome (the “outcome” is the resultant torque on the tibia). In fact, the length of the effective lever arm is just as important as the binding’s force-setting (the “effective lever arm” of the above reported bindings is not aligned with the long axis of the tibia — thus the lever-arm of pintech bindings is not effectively same as that of the tibia. Here in the above graphs we can see that when we do fall (noting that no binding can guarantee 100% injury free skiing) different binding designs produce different resultant loading on the tibia — independently of the binding’s release force settings.

    Further — and yes, Lou — lowering the release settings (adjustable release settings are not avaliable on several types of pintech bindings) is UNWISE because lower-than-recommended settings can produce pre-release. All of us experienced skiers know that pre-release has the possibility of causing upper-body injuries that can be far more severe that tibia fracture.

    There are two distinct types of pre-release. One is precipitated by ‘steering mistakes’ (“steering”) and the other is called “disturbing”. These terms have found their way into the English from rough translations of their use German, Austrian and Swiss skiing safety research. ‘Steering’-precipitated-pre-release is obvious in its origin: we’ve made a self-induced skiing mistake. ‘Disturbing’-precipitated-pre-release is caused by what ski binding engineers call ‘snow snakes’ (snow grooming equipment cat tracks, chunks of half-frozen ice under the snow surface, ice-cracks hidden under the snow, etc.). Binding design is advancing significantly these days to provide outstanding anti-pre-release (retention) in the face of ‘disturbing’ events. The newest binding designs reach far beyond mere ‘elasticity’ and ‘recentering’ to provide outstanding retention. Binding engineers have discovered that ‘functional decoupling’ and ‘controlled kinematics’ ADD far more retention-capacity than elasticity and recentering alone. But not amount of advanced retention features in a given binding design can avert a ‘steering’-induced pre-release other than to have a minimum setting that provides opposing-resistance to the infrequent skiing-mistake that we sometimes make. This is why a minimum setting is needed to mitigate pre-release irrespectively of advanced retention-features in any binding design … and the above paragraph noting that release settings by themselves cannot off-set a given binding’s DESIGN in terms of its lever-arm configuration (to provide effective release characteristics).

    So, in conclusion, when we do experience a fall while noting that no binding can provide a 100% guarantee of injury-free skiing, the significant variation that’s found in ski binding design does have a direct material effect in the biomechanical response of the tibia, INDEPENDENTLY of release settings, per se — though release settings do play a role in both the biomechanical-response AND in mitigating pre-release, too. Do not underestimate the effect of a given binding design because the DESIGN controls the role of the ‘effective lever-arm’ — and the ‘effective lever-arm’ is JUST AS SIGNIFICANT in Newton’s basic equation as is ‘force’ (the release force supplied by a binding’s release setting). Binding design counts.

    Rick Howell
    Howell Ski Bindings
    Stowe, Vermont USA

  123. Jim Milstein January 18th, 2015 8:20 am

    Well said, Lou. Thanks, also, for the part about action-packed hut trips. In my prime I skied with Beglinger in the Selkirks, but seven Beglinger days were too much for most mortals. I always took a rest day in the middle to watch the pine martens play. Nevertheless, I was wiped out by the end.

    The “somewhat hidden terrain features” include branches, snags, and logs under the snow. X-ray vision helps. You can develop it.

  124. Lou Dawson 2 January 18th, 2015 8:43 am

    Rick, yes, no way should anyone do anything that increases chance of accidental binding release! But at the same time, I’ve seen skiers who set their release values ridiculously high to prevent pre-release when they could fine tune their settings and perhaps get a better balance of protection. More often than not, you see pintech skiers skiing at higher settings than they need to, hence I’m always nagging about folks being more nuanced with their settings. Lou

  125. Jim Milstein January 18th, 2015 11:08 pm

    Rick’s stat of 80% of ski injuries due to falls got me wondering. Maybe the rest are from collisions. So, the second principal strategy to avoid injury might be Do Not Collide. (The first is Do Not Fall)

    However, if a bunch of ski injuries result from heart attacks, strokes or fights, I am stumped.

  126. Lou Dawson 2 January 18th, 2015 11:24 pm

    I’d guess collisions make up the bulk of the remaining 20%, Rick?

  127. Rick Howell January 19th, 2015 6:24 am

    Yes, collisions and ‘other anomalies’.

    But let’s go back to the issue of how equipment can help during most of the 80% of injuries that are caused by falls (but in which bindings cannot guarantee 100% injury-free skiing) — especially the last comment about pre-release and high settings.

    Living here in Stowe, Vermont; working on the engineering of bindings up on the mountain here in Stowe (while MEASURING release; MEASURING retention); and skiing for fun here in Stowe, including BC skiing Bolton-Trapp — we’re surrounded all day by high settings among good skiers. In my decades of engineering research, I find that good skiers do not elect to have high settings by choice. High settings are selected because of poor binding DESIGN in order to not pre-release. Bindings with poor retention characteristics, not just from poor ‘recentering and elasticity’ — but more importantly, poor retention characteristics from:

    (a) poor ‘functional decoupling’ between a given binding design’s release-function and its retention-function;

    (b) poor ‘control of the kinematics’ between the boot and the ski within the path of the release-function and the retention-function.

    Binding designs with poor retention characteristics (poor recentering, poor elasticity, poor functional-decoupling, and poor kinematics) — demand high settings to offset the inherently poor binding design.

    The solution to reducing the scourge of high settings is to utilize binding DESIGNS that feature good retention characteristics. In this way, release is decoupled from retention — thereby averting the need for high settings to mitigate pre-release.

    One of many examples of this aspect of binding design is to note whether the ski-boot-binding system (SBB) is ‘moving toward release’ during controlled skiing maneuvers. If it is, then the binding’s release-function is not functional-decoupled from its retention-function. Controlled skiing maneuvers should not cause the binding’s release-features to become stressed (or activated). Only injury producing loads should cause a binding’s release-function to become activated. Most of the ‘other’ bindings that I measure deploy release-features that become activated during controlled skiing. This is bad. This requires high settings — in an attempt to off-set poor design. I call high-settings: “design deficiency settings”.

    Functionally decoupled ski-binding designs (that also deploy the other basic A-B-C’s of retention) DO NOT require high settings to avert pre-release. The choice we make should not be the height of the settings: the choice should be binding DESIGN (designs that provide decisive decoupling).

    Rick Howell
    Howell Ski Bindings
    Stowe, Vermont

  128. See January 19th, 2015 7:38 pm

    Thanks all (especially Jason, Rick, and of course Lou) for this important post. As a side note: today I was reminded of an obscure piece of hardware from the distant past that puzzled me at the time. Now, decades later, I think I understand the concept behind the Allsop binding. And the little peg that fit in the boot sole was the precursor of the “power tower?”

  129. Jim Milstein January 19th, 2015 7:47 pm

    Voilé used to make a releasable plate to be used under a 70mm Nordic Norm binding. It released upward too. That was a bug, not a feature. If the skier had a wad of snow under foot, the ski could come off when the skier put his/her heel down. Most annoying.

  130. See January 19th, 2015 8:18 pm

    They worked well for me. Never had the problems you described, but I only used them on my first pair of alpine boards mounted tele.

  131. See January 19th, 2015 8:23 pm

    I had a certain degree of confidence because they were a variation of the alpine plate bindings which seemed to work ok.

  132. See January 19th, 2015 8:52 pm

    … at least to the side (laterally).

  133. Rick Howell January 20th, 2015 8:32 am

    Yes, See, the Alsop binding was a major critical binding in the history of skiing-injury research. There were so many tibia fractures with this binding in 1972 that it prompted researchers to take a close examination of it. We may have developed the single biggest ski-binding/biomechanical research tool, ever, during the exploration of the Alsop fracture problem. Case Western Reserve University Professor Gene Bahniuk, PhD, (previously, the developer of Ford’s 1st fully-hydronic backhoes; & a true genius mechanical engineer) developed the ASTM F-504 test method (which is also, today, ISO 9462 Method-B) as a consequence of the Alsop failure. These were the 1st test methods to explore what happens to the leg in the presence of applied ‘release envelopes’ — where simultaneous incremental torsional-torques & incremental bending-moments were measured on a simulated metallic tibia.

    The test results clearly illuminated the exact problem with the Alsop binding: its pivot-point in torsion (defined by the Alsop-peg located under the ball of the foot) created a blind-spot. In other words, & as an extreme example, when one of the incremental forces within the full envelope was applied to the side of the ski, laterally, to the Alsop pivot-peg — the force required to cause binding-release approached infinity … while at the same time, torsional-torque about the tibia, increased correspondingly. Why? Because, the force that was applied next-to the Alsop pivot-peg was located a distinct distance away from the projected axis of the tibia. Therefore, a torsional-torque was applied to the tibia, while at the same time, the binding ‘sensed’ zero torsional-torque even while the applied force (at this location) approached infinity.

    Although lateral forces are not always applied to a ski directly-lateral of the ball-of-the-foot where the Alsop peg was located, never-the-less, the effect of this blind-spot caused an adversely-added torsional-torque to be generated within the tibia when lateral forces were applied to all other points within the full envelope along the length of the ski.

    This finding caused a true revolution in the testing of ski-bindings at the design-engineering level — especially because a “release check” (as Lou sometimes references above) revealed no problem.

    The full-envelope test method created by Gene Bahniuk, then adopted by ASTM and later by ISO, revealed the powerful significance of the effect of various binding’s pivot-point locations relative to the tibia — and revealed how the corresponding variation in the effective lever-arms by differing binding DESIGNS produced hugely significant effects on the tibia, sometimes (as in this case) producing an even bigger effect on the tibia as does the adjustable variation that’s possible with adjustable release-force. With Alsop, we measured a 300% increase in torsional torque about the tibia — when compared to a “release check”.

    This test method was then utilized to vet-out other horrendously bad bindings of the time, such as, for example, Americana.

    Here, in this dramatic example with Alsop (& Americana), we can clearly see what happens when a binding’s pivot-location along the length of the ski is not aligned with the long-axis of the tibia. These follies in engineering caused a systemic biomechanical failure that resulted in thousands of fractured tibias. As soon as the epidemiological evidence plus the results from new test method illuminated the problem, the two Alsop brothers immediately removed the Alsop binding from the market.

    Now that this great illustrative point with the failed Alsop binding design is illuminated here in this thread (thank you, See, for bringing-up Alsop) — we should all contemplate where the lateral pivot-point is located in pintech bindings — then contemplate the effect on the tibia (as is clearly shown in the above graphs).

    Rick Howell
    Howell Ski Bindings
    Stowe, Vermont

  134. jbo January 20th, 2015 9:13 am

    Rick – does the Alsop get any credit for moving the fulcrum of forward bending closer to the ball of the foot, where modern alpine bindings have it positioned? As we have shown, having the fulcrum positioned close to the boot tip in tech bindings effectively increases forward bending moments relative to alpine bindings with similar settings.

  135. Wynn Miller January 20th, 2015 9:49 am

    Thanks for this

  136. Rick Howell January 20th, 2015 9:54 am

    @ jbo — The leading edge of Alsop’s plastic plate that formed the position of forward pivot point did move the effective lever-arm in forward bending closer to the natural biomechanical point of rotation in forward bending. However, my prototype racing bindings (1st hand-made in 1969) had the leading edge of the Teflon AFD’s positioned a full centimeter further aft of Alsop.

    By moving the fulcrum for forward release aftward (as defined by the front-edge of the AFD), not only is the bending-moment blind-spot to the tibia mitigated — but so also is edge control improved if the binding’s peak forward bending moment is re-calibrated.

    Edge control is also improved when the forward-bending pivot is moved aftward because in order to maintain a constant peak forward bending moment with a shorter forward lever-arm, the peak release force at the heel can be increased. (ISO 8061 specifies recommended peak forward release TORQUE, not force). Because almost all ski-binding’s heel’s forward release mechanisms are cross-linked with the ‘roll mode’ (cross-linked with edge control) — edge control is also improved because the same force that’s part of the equation to control the forward bending moment is also part of the equation governing edge control.

    Therefore, by moving the forward pivot aft, it’s possible to increase the hold-down force at the heel to improve edge control, while at the same time holding the peak forward bending moment at release constant !

    Moving the forward release fulcrum aft improves skiing performance without sacrificing recommended release.

    All pintech bindings behave in the opposite way, adversely.

    Rick Howell
    Howell Ski Bindings
    Stowe, Vermont

  137. Bruno Schull January 25th, 2015 5:36 am

    @Rick. Your understanding and command of the nuances of binding design are impressive. If I was a rich man, I would invest the money to help you develop your binding, but regrettably ‘m not that position.

    I wondered if you might say a few words about elasticity. We often hear that word in relation to bindings, but what does it actually mean? Some kind of progressive resistance against a spring? Degrees of freedom the prevent your foot from being locked rigidly in place? A kind of shock-absorbing, or suspension, system, that works over a small distance to absorb forces transmitted through the ski? Does it help protect soft tissue? Does it help control a ski? And so on.

    I would also appreciate your thoughts, Lou. Your ability to cut through the bull, and issue straightforward, common-sense advice is as impressive as Rick’s knowledge of bindings.

    Many thanks,


  138. Lou Dawson 2 January 25th, 2015 7:18 am

    Thanks Bruno, I can tackle that a bit but I’ll probably get the terminology wrong. I can say that in my view, ski binding elasticity refers to the ability of the binding to to store or absorb force introduced by the binding and boot moving in relation to each other. Force is “absorbed” by a suspension system when the kinetic energy is converted to heat, such as with a shock absorber on a car. A ski binding would usually “store” force in the springs, re-applying it to the boot to return the boot to its centered position in the binding. Some of the force would be absorbed due to friction in the moving parts. I think that’s a layman’s interpretation, anyway. Like I said, my terminology is probably off. Lou

  139. Bruno Schull January 25th, 2015 7:52 am

    Thanks Lou. That is roughly what I gathered. I think the analogy to a shock absorber is apt, and I am familiar enough with shocks on bicycles to understand the concepts of kinetic energy, heat, friction, and so on.

    In more general terms, is elasticity good or bad? How does it affect skiing? Is is something we should want more of?

    All the best,


  140. Rick Howell January 25th, 2015 8:33 am

    Hello, Bruno — A few skiers may remember way back in 1979 when I wrote an article in the December issue of SKI magazine (page 124) on the relationship between ski-binding elasticity and other ski-binding design-parameters that pertain to the functional requirement of on-slope retention. That article was an off-shoot of my writings from my experiences while working as an apprentice in high school during the late 1960’s for Gordon Lipe, from ski racing at a fairly high-level, from my co-development of #1-selling bindings for Salomon in the early 1970’s, from my engineering-thesis at MIT’s Charles Stark Draper Labs and from my on-slope service center at the finish line shack at Pat’s Peak ski area in New Hampshire where I catered to elite racers (while being one, myself). My writings on this topic then became the 7-page introduction to the Geze ski binding Technical Manual for a number of years during the late 1970’s and early 1980’s.

    For a complete answer to your question — the subject is addressed in reasonable depth within those manuals. Thousands of ski-shop employees throughout North America were required to read about this topic as part of the Geze ‘Dealer Indemnification program’. Some of us here on Wildsnows who worked at ski shops back then may remember these writings because — as part of the Certified Ski Shop Technician program, a test was taken that traversed this topic on ‘elasticity’. Again, the best answer is a complete-answer — which can be found in my early writings in the 1979 issue of SKI magazine and in the Geze Technical Manuals surrounding that time period.

    Here is a short — but incomplete — answer:

    Ski-binding ‘elasticity’ is defined as the functional-interaction between an innocuous load that enters the ski during all forms of controlled skiing — and the resistive properties of the ski-boot-binding (SBB) system that include inertia, stiffness and friction as a function of the displacement between the boot and ski/binding and the duration of the load.

    A good binding design must allow the ski to move away from the boot (or, in an equal-magnitude, opposite-direction sense — the binding must allow the boot to move away from the ski) and then cause the ski to fully-return to its original position.

    ‘Elasticity’ is one of 3 key sub design parameters (sub-DP’s) that provide one of the two main design parameters for the functional requirement (FR) of retention. The other 2 sub DP’s are ‘controlled kinematics’ and ‘functional decoupling’. Elasticity—together with the other 2 sub DP’s—provides a way for a mechanical binding to resist innocuous impacts (disturbing loads) within a ski-binding’s modes of release: it allows a ‘temporary release’ until the innocuous load goes away. Too much elasticity can delay necessary-release: therefore, the magnitude of elasticity must be optimized.

    Practically speaking from an engineering perspective — because the ‘peak stiffness’ of a binding is regulated by the standards that define ‘peak release, and because the inertia of a SBB-system is largely ‘constant’ and not adjustable— this means that the remaining two variables that can be controlled by design are friction reduction and the amount of displacement before release that provides full return of the ski to the boot (though, again, too much displacement can delay ‘necessary-release’ during fast, dynamic, injury-producing loads). Friction reduction determines the ‘efficiency’ of the elasticity. The less friction within a SBB-system, the better a binding is able to return the ski and boot to a fully centered position. For example, imagine a ‘Slinky’-spring being connected on one end to a wall; stretched across a carpeted floor; the let-go at the other free-end. Compare the behavior of the Slinky-spring to what would happen when it was let-go across a formica-type floor. In the first case with the carpeted floor, it will move slow and may not return to its original fully-compressed status. Reducing the friction of the floor—as with the formica—is a sure way to enable better return. This analogy also applies to ski-bindings in all modes-of-release — and provides emphasis toward how critical it is to properly utilize low-friction materials and to design low-friction mechanisms into any ski-binding’s moving interfaces.

    Low-friction elastic characteristics provide fast recentering. If, immediately after an encounter with a innocuous impact, a binding can quickly recouple the boot and ski to the centered-position, the SBB is then ready to provide repeated elastic behavior for an encounter with the next innocuous impact. The next encounter might be a millisecond later. Taking the adverse view — if the binding does not provide rapid and full recentering, multiple innocuous impacts will cause the SBB-system to incrementally progress to an unwanted release … a pre-release.

    But elasticity alone is no panacea for retention. We know bindings such as Spademan and the old Look Nevada that had significant ‘elasticity’ — but yet these bindings pre-released at ‘normal’ settings all the time. That’s because those bindings did not — in the case of Spademan — provide functional-decoupling between the various release-modes; and in the case of the old Look Nevada, it did not provide properly controlled-kinematics. It’s just too much for me to elaborate further today here in Wildsnow on the full meaning of ‘functional-decoupling’ and ‘controlled-kinematics’. Maybe later. Maybe.

    Please also note that everything I’ve described above about averting pre-release (or, ‘providing proper retention’) is in the context of dealing with innocuous-loading from the skiing-environment, such as encountering a chunk of ice, hitting cat-tracks, slamming into bumps, riding through abrupt transitions, … etc. An accepted term from a rough-translation of the German for this aspect of ‘retention’ is what’s called encounters with “disturbing loads”. The other aspect of retention deals with “steering loads”: this term that’s roughly-translated from the German is intended to mean — dealing with ‘skier-error’. Elasticity cannot abate mistakes in skiing technique that are induced by the skier. Technique mistakes by skiers can cause pre-release irrespectively of all of the best sub-DP’s that are deployed in a good binding, including the utilization of good elasticity.

    Those are my thoughts today on ‘elasticity’. 🙂 ‘And that’s enough for today. Now, it’s time to go skiing here in Stowe, Vermont. The conditions are excellent!

    Rick Howell
    Howell Ski Bindings

  141. Rick Howell January 25th, 2015 8:45 am

    @ Lou — Now that I’ve written my note, above, I now see Lou’s response to Bruno.

    Unfortunately and respectfully, it is a myth that there is appreciable ‘absorbtion’ of anything in a ski-binding — except with Marker’s new ‘Active-Damping’ toe-piece in their racing bindings. This comment is not about terminology: it’s about a conceptual distinction in basic physics. ‘Elasticity’ is described in my post, above.

    Further, from a practical perspective — one of the most direct ways to determine the effectiveness of a ski binding’s complete retention capabilities relates to how low it can be set for release and still provide retention. At the end of the day, that’s the bottom-line. As an example, today’s top alpine binding toe-pieces rarely pre-release at normal release settings. This is because all of the above DP’s and FR’s are well organized in today’s alpine bindings. On the other hand, several of today’s alpine heel-pieces pre-release all the time at normal settings. Simply put, this is because the designs of these heel pieces have not deployed all of the FR’s and DP’s that I note, above. Remember, ‘release’ does not equal ‘retention’. These are two sides of the same coin. 🙂

    Now, skiing ! 🙂 🙂

  142. Rick Howell January 25th, 2015 8:47 am

    Typo correction: “This is because all of the above DP’s and FR’s are well organized in today’s alpine bindings.” — should read: “This is because all of the above DP’s and FR’s are well organized in today’s alpine binding toe pieces.”

  143. Rick Howell January 25th, 2015 3:40 pm

    2nd typo corection: “For example, imagine a ‘Slinky’-spring being connected on one end to a wall; stretched across a carpeted floor; the let-go at the other free-end.” … should read, “For example, imagine a ‘Slinky’-spring being connected on one end to a wall; stretched across a carpeted floor; then let-go at the other free-end.”

    Also I would be fully remiss to not add that it’s not Lou’s ‘myth’ about “absorption”: this is a common myth that’s even contained within some of the existing standards.

    Lastly on the subject of ‘elasticity’ — please image pintech bindings with elasticity: THAT would be helpful.

  144. See January 25th, 2015 8:37 pm

    I don’t expect any one to touch this with a ten foot lever, but how would the Vipec (sliding toe), the Kingpin (more springs), and the Beast (turntable) compare in terms of lateral elasticity, functional decoupling, and controlled kinematics?

  145. Rick Howell January 25th, 2015 8:47 pm

    Ha-ha ! ‘Good one !! I’ll be happy to tackle that question, for …

  146. See January 25th, 2015 8:48 pm

    I realize a proper answer would involve testing which (if it exists) is not likely to be shared, but I mostly propose this as a thought experiment that might be illustrative of the binding properties in question.

  147. See January 25th, 2015 8:50 pm

    But if you take a pass, Rick, that’s totally understandable. Your generosity with your knowledge and experience is really appreciated.

  148. Rick Howell January 25th, 2015 8:58 pm

    Hello, See. Talk it over with Jason Borro. 🙂

  149. Wynn Miller January 25th, 2015 9:15 pm

    “During the course of the trial, uncontroverted evidence was presented to the effect that although no binding could be set at a tension sufficiently low to release during a slow fall and still keep the skier on his skis during normal skiing.”

  150. Rick Howell January 25th, 2015 9:21 pm

    I’m not even reading the link because that’s patently untrue. I raced on a World Cup DH course at Whiteface Mountain in 1977 finishing 5th; then twisted-out of my bindings, s-l-o-w-l-y at the finish line (without breaking my tibia). That binding also produced a nearly perfect 3D ‘cubic envelope’ during development tests. (( I could also slowly self-release out of the heel. )) ((( Also, most release springs are under compression, not tension. Tension in a spring causes unwanted vibration. ))) 🙂

  151. Kristian January 26th, 2015 5:59 am

    Here is what I suspect:

    High speed fall – you are tumbling; the ski directly strikes the slope transmitting great direct shock force to the binding and it immediately releases.

    Slow twisting fall – skis are almost stationary; your upper torso is twisting and falling off slowly backwards; all of this force is transmitting down through your trunk, through your legs; it has to pass directly through your knees; and here your knee ligaments get wound up like a rubber band on a cheap balsa toy airplane.

    Your ski bindings are almost wholly shielded from all of this torsional force by your knees above them.

  152. Rick Howell January 26th, 2015 6:12 am

    @ Wynn : Ok, I read the ruling from the court. Just about no one could ski without pre-release in Cubco bindings that were made in 1967. They were probably the worst bindings ever made. They should be the ‘bad example’ to explain what happens in the absence of ‘functional-decoupling’. Worse, the evidence put before the court indicated exactly what you quoted, Wynn. This evidence is ‘fact-specific’ AT THAT TIME: the bindings were purchased in 1967 !

    Starting in the mid-1970’s, several alpine bindings (coupled together with the related release recommendations from the same alpine binding companies) were available that could allow ALL (healthy) SKIERS to ski aggressively at settings that were as much as 50% below the fracture limit of the tibia in both torsion and bending throughout a 3D envelope that excluded the non-ASTM-tested hole in the between -45cm of the projected axis of the tibia and +45cm of the tibia — while simultaneously mitigating pre-release. ALL TÜV certified alpine bindings that are available today allow ALL (healthy) SKIERS to ski well-below the tibia fracture limits in torsion and bending while simultaneously mitigating pre-release. This point does not hold for pintech bindings. Of course, no binding can guarantee injury free skiing. Injury can result from simply falling-down or from impact with another object or skier. Further, as noted above, pre-release can be inadvertently self-induced by a skier due to error in skiing technique.

    Old case law like that needs to be compartmentalized as ‘history’: the ‘facts’ from bindings that were made in 1967 bear no relevance to today’s available-technology and available know-how.

  153. Rick Howell January 26th, 2015 6:40 am

    @ Kristian: There is no need to speculate. Repeatedly solid engineering science shows that the tibia fracture limit in both torsion and bending is lower during slow loading than in fast loading (‘fast’ = greater than 0.1 seconds, where tibia strength is ~18% stronger).

    In regard to ACL-ruptures — again — there are several different ‘injury mechanisms’. One mechanism is BIAD (Boot Induced Anterior Drawer). This ACL-injury mechanism has a prevalence today of ~8% of all skiing-ACL injuries. Another mechanism is Phantom Foot / Slip-Catch: they have a combined prevalence of ~80% of all skiing-ACL injuries. BIAD is caused by pure or dominant rear-weighting, especially when the tail of the ski is loaded (in your case — when the tip is pulled straight-under you in the snow, it’s the same loading mechanism as BIAD). Phantom Foot and Slip-Catch are valgus-dominant injury mechanisms — there is VERY LITTLE ‘torsional loading’ (please see graphs at the top of this thread to discover the ratio of valgus-moments to tibia-torques at release when a load is applied to the ski where valgus is dominant). Valgus-dominant loading (such as in the 80% prevalent Phantom Foot and Slip-Catch falls) IS read and reacted-to by a binding with lateral heel release that has ‘proper’ settings for valgus release (again, please see above graphs). A binding CAN read and react to valgus-domant ACL-injury mechanisms IF the binding provides lateral heel release that is adjusted to do so. In the case of the 8%-prevalent BIAD mechanism (yours), a binding with vertical toe release can read and react to it, if adjusted to do so. Unfortunately, there are no bindings on the market today with pure-vertical toe release that’s independently adjustable.

    ‘And, yes — as with the tibia — the ACL and MCL are also about 18% weaker during slow-loading as compared to fast-loading that’s faster that 0.1 sec. throughout the entire applied-load. Slow loading is the worst-case scenario. and Alpine binding release technology addresses worst case, slow-loading. The difference in pintech binding behavior during slow and fast loading (throughout a full release envelope) is presently unmeasured.

    Please also note that a tibia or an ACL does not know if one is utilizing an alpine binding or a pintech binding.

  154. Wynn Miller January 26th, 2015 8:26 am

    Wish we had the trial transcript to see how the attorneys for Cubco and plaintiff argued the state of the art in 1974.

  155. Jim Milstein January 26th, 2015 8:57 am

    I skied on Cubcos for a couple of seasons in the fifties. It’s true that they were poor bindings from a skiing point of view (great entry and exit), but I don’t recall prerelease being a problem for me. I’ve not had a leg or knee injury skiing, so I don’t have much to say about that beyond noting the several decades spent using mostly non-releasable tele bindings. My rules: Do Not Fall. Do Not Collide. Usually honored.

  156. Rick Howell January 26th, 2015 9:55 am

    @ Jim Milstein: The incidence of skiing tibia fractures back in the mid-50’s appears have been ~400 mean-days-between-injury (MDBI) thus, your individual situation would — from a probability perspective — fall somewhere within the context of that injury rate. You might have been in the 95-percentile, too (just short of 800 mean-days-between-injury) in terms of your exposure at risk. We’ll never know where you were on that bell curve.

    The ‘individual-experience’ situation relative to ski-binding injury mitigation is kind of like commenting on the effectiveness of our cars’ air-bags after driving a year. It’s difficult to evaluate the effectiveness of our air-bags in this way.

    However, when we experimentally-measure resultant release (torsional)-torques, bending-moments and applied-forces (collectively, ‘loads’) — biomechanically — as displayed in the multi-dimensional envelopes shown at the beginning of this thread — relative to established biomechanical limits — we can then evaluate the effectiveness of a given ski-binding’s release-performance.

    An accurate epidemiological evaluation (a prospective intervention study) of a given ski binding requires a sample size of ~30 skiers who ski all day every day for about a season; then requires a comparison to the ‘average binding release-performance’ within a validated ‘control population’.

    That’s why — of the two approaches to two evaluate the release performance of a given ski binding; epidemiological, or biomechanical — it’s more practical to utilize biomechanical testing than individual experience (nearly statistically-impossible, today, with the control population of tibia fractures having a MDBI of ~20,000).

    However, with biomechanical testing, we can see accurate results on ski-binding release performance after a few days and several hundred experimental release tests.

    Cubco biomechanical tests were presented at one of the first ASTM meetings in the early-1970’s. The results were horrendous. Cubco immediately withdrew from the market. As for Cubco pre-release, that’s another story, another day. 🙂

  157. Rick Howell January 26th, 2015 10:11 am

    @ Jim Milstein (2): Another way to look at this is, again, the car air-bag analogy. If we avoid getting into a head-on collision in order to avoid knowing for sure whether our cars’ air-bags function effectively or not — are we in a position to evaluate the effectiveness of our ski-bindings’ release-function when we take the same approach by not falling?

    Just like with crash-testing cars while utilizing biomechanical dummies to learn about the effectiveness of our cars’ air-bags — the best information we can gather on ski-binding release-performance comes from conducting experimental tests that form the full release envelopes that are shown at the top of this thread.

  158. Rick Howell January 26th, 2015 10:34 am

    This is a great group with great comments.

    By now, I’m confident that we have good group-think on this important topic about the interaction between all forms of ski-bindings and our bodies.

    By now, I’m confident that there a growing understanding about the significance of full-envelope release testing. The concept behind this method of evaluating a ski binding eliminates the guess-work about ‘fall mechanisms’ and reaches beyond the questions about ‘what happens if / when I fall?’ Full-envelope ski binding release testing explores EVERY possible load configuration — and when a single test within the full envelope of release testing pokes-through the biomechanical failure limit of the tibia or the ACL, we don’t need to guess anymore about fall-mechanics or which way a fall might have occurred: in the given individual loading condition within the full-envelope of tests, the binding simply failed to release before the biomechanical injury threshold was reached. This is big. It cuts through all of the guess work and comes right to the heart of the release matter.

    Rick Howell
    Stowe, Vermont

  159. Bruno Schull January 26th, 2015 1:02 pm

    This is an amazing thread. The amount of useful information, and the level of civility, is high. I think that speaks volumes about the environment created by Lou, and the reader base. Nice to be a part of this community.

    @Rick, I have two general sets of comments, that I will separate into two posts. The first is about testing, funding, and trends in the industry. The second is about binding design.

    I think you have made a strong case for quantitative testing—what rational person would not agree? It also seems that the ski industry, over the years, has performed at least some of this testing, and incorporated results into standards, although they could be improved. For example, improvements in binding design—due in large part to the discovery process of testing and to epidemiological studies—lead to greatly-reduced rates of tibia fractures.

    One thing I find interesting is that the same attention seems not to have been applied to reducing soft-tissue injury. It may be a generational thing—I have only be skiing for about a decade. I started in about 1995. What always scared me about skiing was tearing my ACL, not breaking my tibia. I don’t know if that’s simply because I was ignorant, or if, by the time I started skiing, tibia fractures had already become less common, and so there was relatively less awareness of broken bones, and relatively more awareness of soft-tissue injuries. Perhaps there were even more soft-tissue injuries in absolute terms. Did new binding designs solve one problem (broken tibias) and create another (soft-tissue injuries)?

    What are your views on how the industry processes this information now? Do manufacturers regularly do this kind of testing? Is there enough knowledge, experience, and motivation in the ski industry? Do you think we will see improved bindings in the future?

    In your case specifically, what I understand is that you would be happy to perform as much testing as needed—if you had the money. Likewise, you would be happy to get your binding to market—if you had the money. One post above suggested that if everybody donated a small amount, we might be able to get enough money together to perform some quantitative tests on a range of touring bindings. I would contribute to that effort. But perhaps we need to think bigger.

    If I am not mistaken, there are a variety of relatively easy platforms to advertise “crowd-sourced” projects. Maybe you (or somebody else) could set up a crowd-souring platform to support binding testing, or even to help bring your binding to market. We’ve all heard the stories about the crazy things that have been funded on the internet—why not bindings?

    OK, those are my thoughts for now. I will try to formulate my specific questions about binding design in a following post.

    All the best,


  160. Bruno Schull January 26th, 2015 1:03 pm

    Post number two. Binding design.

    First, I would like to say that I completely understand if you don’t want to answer these questions because 1) you simply don’t have time, and 2) doing so would reveal information about your design that you do not want to share. I respect that. Life is short and words take time. It’s not like you have all day to sit around educating people about binding design. Likewise, as you have spend a lifetime studying bindings, there’s no reason you should not expect something in return for your

    But I’ll go ahead and ask my questions anyway. There’s no harm in asking. As a high-school science teacher, and general engineering-minded person, I can’t resist my curiosity.

    If I understand correctly, alpine bindings are “good” for your tibia because they have lateral release at the toe, while touring bindings are “good” for your soft-tissue because they have something like lateral release at the heel, albeit, lateral release with a fair amount of friction, complication from the toe unit, and performance variability. It follows that improved bindings, both alpine and touring, would have lateral release at both the toe and heel, as well as functional decoupling between retention and release.

    The first thing I don’t understand is how you can actually functionally decouple retention and release.

    I don’t really know how ski bindings work, but if I’m thinking along the right general lines, the springs that hold your boot in place are the springs that must be overcome or forced open before your boot releases. Therefore, release and retention involve the same springs. So as bindings are designed now release and retention are not decoupled.

    It’s hard for me to imagine a system in which release and retention were decoupled. I guess you could have one set of springs that served the purpose of retention. These springs could hold the boot in place, allowing is to move a few degrees, before returning it to center, hopefully with a smooth, low-friction movement. Then you could have another set of springs that served the purpose of release. When forces increased past a certain threshold, or the boot moved a certain distance, these springs could release the boot. However, in such a system, you would still have to overcome the “retention” springs before the “release” springs engaged. Furthermore, the “release” springs would presumably themselves have some range of motion in which they flexed before releasing—and you would return to square one.

    I can also imagine a release system based purely on boot movement, for example, if your boot was displaced a certain number of degrees, it would lift out of the binding. I guess, in a design like this, you would have to enter the binding the same way, but I don’t know how it could be incorporated with the retention system and parallel systems for vertical movement.

    The second thing I don’t understand is how a binding with lateral release at the toe and heel would still allow you to ski effectively without pre-release. Again, I don’t really know what forces are involved, but I imagine this is a main difficulty. It would seem that if a binding has many degrees of freedom and a low release threshold, it would necessarily release with lower inputs or forces. Conversely, if a binding has a higher release threshold, it would have less possibility of releasing when needed. You suggest above that the solution to this problem is functional decoupling—but again, how would that actually function?

    So there are my questions. As I said above, I completely understand if you just say, “Nope.”

    Thanks for all your efforts so far,


  161. Rick Howell January 27th, 2015 9:12 am

    @Bruno, No smoke, Bruno, you are an excellent thinker and writer — and you’ve nailed several questions of the hour quite aptly.

    First, I’d like to say that I wish I could write half as well as you. Compounding my poor grammar, I had a head injury 20-years ago that’s made it difficult for me to summarize. I promise all of you that I’m always trying to write and summarize better. Meanwhile, my apologies to all for my overly-long posts.

    I’d like to attempt to tackle your first set of good direct-questions on testing, funding and trends in the industry … then comment on my overall thoughts about these important issues.

    1st, your direct-questions: “What are your views on how the industry processes this information now? Do manufacturers regularly do this kind of testing? Is there enough knowledge, experience, and motivation in the ski industry? Do you think we will see improved bindings in the future?”

    “The industry” is comprised of many sub-groups who impact improved ski equipment performance. The main ones are the ski, boot and binding companies; ski-tuners and boot-fitters, including orthodics-makers; on-snow magazine reviewers; blogs (such as this); independent testing labs; a few dozen university professors and their grad-students that include research orthopaedic surgeons and research engineers; independent epidemiologists; product liability insurance companies; a few retailers (such as Skimo owner, Jason Borro); several clinical MD’s including clinical orthopaedic surgeons, emergency room doctors, head-trauma doctors (including a few brain surgeons) and rehabilitation MD’s; and a few bona fide journalists (such as Seth Masia and Rick Kahl). Just about all of these sub-groups are members of several different organizations including mostly the national trade show organizations, standardization organizations, and skiing safety organizations. Here in the US, the national trade show organizations include (mostly) Outdoor Retailer and SIA. Internationally, the main trade organization is ISPO (Munich). The main standards organizations are ASTM (USA), DIN (Germany), AfNOR (France), Ö-Norms (Austria), BFÜ (Switzerland) — all of whom vote at ISO (international). The main skiing safety organizations that report original research are ISSS (international — with an important 5-day conference coming-up in March in Cortina, Italy … and I encourage all of you to attend), SITEMSH (for mostly MD’s, internationally). Of course, there are the many ski-patrol organizations—all of which are good and important—but none organize original research or development: ski patrol organizations follow standard procedures issued by medical organizations. There is only one organization that enforces equipment standards— the Swiss BFÜ. BFÜ is funded by a consortium of Swiss insurance companies and the Swiss government (Switzerland has determined that skiing-injuries adversely effects the GDP of Switzerland ! thus, enforcement of the standards might lead to an improved Swiss-GDP ! ).

    Each of these groups and organizations have related but slightly different agendas that lead to different levels of up-take and action when it comes to equipment performance (I view equipment-‘safety’ — as one key functional aspect of equipment-‘performance’). The trade organizations are focused on generating revenue for their members; the standards organizations are supposed to provide ‘equal consensus’ from users, producers and general-interest-groups … but, in fact, this is a difficult balancing-act that’s often awry; and the skiing-safety organizations (especially ISSS and SITEMESH) provide a portal to report original research that sometimes leads in the long-term to ‘preventive-oriented’ equipment standards at the standards organizations (especially at DIN, AfNOR and ISO) and new diagnostic, treatment and rehabilitation procedures within the medical-standards boards. The standards organizations (especially ASTM and ISO) are like high stakes poker games because on the one hand, standards mitigate producer risk by providing definition to potential gray-area liability issues, while on the other hand — standards inhibit innovation and can generate legal issues surrounding anti-trust and restraint of free trade. The standards meetings involve real hard-ball — but (almost) everyone involved attempts to be poker-faced in terms of real action. (( A major standards meeting is taking place, today. ))

    In practice, the equipment producers and national governments fund the university researchers. Research flowing from the universities contains bias toward these benefactors, though grant-funding from governments often originates from equipment producers, too (amplified bias). The clinical research orthopaedic surgeons and ER-docs often appear to be the most unbiased due to their individual earning-capacity … but their ability to self-fund sometimes (not always) compounds transparency about self-serving collaborators. My 45-year involvement deep within all of these groups has uniquely allowed me to sort-out where nearly everyone’s funding is derived. The brightest medical researchers are funding-virgins. Historically, there have been only a few. The best ones generate fantastic breakthrough research, then move on to other non-skiing-related medical research (I can name these great people on one hand).

    I have provided this level of detail here in Wildsnow because it allows us to see why there are often confusing signals that arise from these groups. Sometimes the work-products that come out of these groups are based on who shouts the loudest, sometimes it’s based upon who’s the smartest, sometimes is based purely on money, and other times it’s based upon genuine leadership. Everyone that I’ve seen who is involved in a material-way in these organization that has produced tangible results is a good skier (except one, and I will not name him, here).

    Unfortunately — here at home in the US — the American skiing standards organization, ASTM, has been dominated by one loud shouter for over 40-years. ASTM could have had powerful sway at ISO (the international standards organization at which ASTM, DIN, AfNOr, Ö-Norms, and BFÜ have equal say) — but the shouter’s vanity was largely checked by the others at ISO. Not so, within ASTM: our equipment performance work here in the US has been significantly compromised by the shouter (who’s also the one who can barely ski). This person made a giant contribution toward the tibia-fracture solution in the early 1970’s — but he has (ironically) grossly compromised equipment-related advancements that can be reduced to actual practice. That person has also dragged-in a few other ‘colleagues’ who are good orators that have kept the existing paradigm relative to equipment-related knee-friendly technology solidly — and adversely — in place. But age and individual-health is about to provide change. I remain confident that some of the younger people who are patiently moving into equipment-performance leadership roles here in the US will provide an opportunity for new innovation and standard-advancements to have voice.

    Of course all of the manufacturers test, in-house. But in order to maximize profits, large margins and large unit-sales are necessary. Low cost of production, fashion/styling, and innovation are the key product-related drivers to expand margins and profits. Testing leads directly to innovation. But to execute the innovation that’s a spin-off of testing, secrecy must be maintained by the big players (e.g., Steve Jobs) until launch. On the other hand, for a little guy like me, the diffusion of certain information leads to eventual validation of new technologies that would otherwise take decades to validate. Remember, the owners of all of the major binding companies are deceased. The professional managers who now run these companies rely upon their R&D managers to provide them with innovation-direction. Why would a top R&D manager who punches a time clock admit to her CEO that a rogue in the backwoods trumped their work? They won’t. They’ll say to their CEO, “It’s no good: ignore it.” The rogue’s innovation WAS WHAT THEY WERE SUPPOSED TO DO. The R&D manager’s job security is threatened by the rogue and threatened by the rogue’s new innovation. The professional manager (the CEO) must rely upon her R&D manager, and thus — the rogue’s innovation flounders in a collaborative commercialization process …….. until the rogue can source sustainable monetary (and other) resources to call the existing kingpins’ (ha!) bluff. The rogue must come to market, sustainably. But the funding playing-field is The Wild West, too (witness my still-on-going 6-year, multi-million dollar litigation against the investor who stole one of my binding companies — and the effective-pause in the ski industry due to this litigation-disruption).

    Do skiers have an influence in ‘market-factors’ ( e.g., Charles Darwin ) ?

    Yes, of course. However, this is a chicken-and-egg scenario, too. Skiers rarely can have real influence in the world of bona fide ski-bindings because (unlike skis) they can’t be built in someones’ garage unless they skip production-molds and skip standards’ compliance. ( What kind of bindings do we suppose have these ‘skips’? ) Meeting the minimum international standards costs MILLIONS of dollars and years of R&D activity. Certain types of bindings have bypassed this major barrier-to-entry by simply ignoring the standards. There are only 3 binding companies in existence today THAT HAVE BEEN FOUNDED SINCE 1965 that have met the minimum international standards. I will not name them here — but overcoming the standards barrier-to-entry is not for the fainthearted. Huge entrepreneurial risk must be brandished to jump the minimum-standards compliance business-hurdle. One ‘go-around’ to this barrier is to “reclassify” a binding: but is this brand of ‘going-around’ in the best interest of unwitting consumers?

    Long-term, one key element of a sustainable-solution involving bindings that meet the minimum standards is to invest in biomechanical and product testing (with bona fide measurements) that can foster exploration of unresolved research, provide demonstration of new innovation that have been developed from the research, and provide product calibration for standards-compliance.

    So yes, Bruno, this is the full-circle, in-practice.

    The ACL-problem, summarized: Some nuts are harder to crack than others.

    I believe that the engineering-mindset (not the actual technology) that led toward solving the tibia problem — caused mental-blocks regarding the ACL-problem. The gigantic 15-year (from 1960 to 1975) focus on tibia’s (which focus led to tibia-friendly skiing, starting 40-years ago — and generated real hero’s in the field) has literally led to a myopic view about the ACL (and MCL) problem. As a crude but real example, if one talks with a binding engineer from a major binding companies a cocktail party, one quickly learns that the mental picture that’s operational is all about the tibia. But the best independent orthopaedic researchers (such as Tom Andriacchi) have proven beyond a shadow of a doubt that tibia-torque plays a hugely MINOR role in ACL-strain. Further, the major driver — valgus-moments — is NOT EVEN MEASURED by other ( I’m still the only binding engineer in the world who is measuring valgus AND the only binding engineer who is applying loads to the middle-thrid of the ski ! ). How outrageous! This industry-wide malaise is, IN-PART, at the root of why we don’t have the ACL problem resolved in a commercially robust way.

    Running through these brick walls by people like me who are at the edge of aging (I’m 62) will not solve these systemic problems within the industry. The solution is through education to the masses of skiers who SUBCONSCIOUSLY DEMAND a solution to the ACL-problem (and with the ‘re-classified’ bindings — the inevitable return of the tibia-problem). This is where the deep skiing experience and sharp thinking of Wildsnow bloggers might actually lead, in-part, to an eventual disruption within the existing paradigm. I believe that this groups’ collective experience and rational thinking-power might provoke an ‘effect’. A solution to the ACL-problem does exist. It is now, as you aptly point-out, a matter of organizing a sustainable platform to bring forth the ACL-solution (and other solutions to meet existing tibi-related standards) in a way that’s sustainable. Here, again, Bruno — your thoughts on the possible mode of crowd-sourced funding might be a worthy route toward making these goals take place in the near term.

    How might we proceed?

    Rick Howell

  162. Wynn Miller January 27th, 2015 9:54 am

    Lawsuits tend to get manufacturers’ attention. Another approach is legislation. We’re lucky in the sense that leading skiing states such as Vermont, California and Colorado include people who are active enough to encourage state governments to enact progressive laws, e.g., California automobile emissions standards and Vermont healthcare and Act 250, which require outfits wishing to do business in the state to toe the line. Bills or initiatives could require all bindings sold in state to address valgus moments.

  163. stefan January 27th, 2015 6:43 pm

    i live in Massachusetts and would like my bindings adjusted by someone knowledgeable. Fritschi Vipec Alpine Touring bindings are not known by most shops and I am nervous about a misadjustment that could be dangerous. are there any recommended shops/ techs I should go to? thanks.

  164. Jim Milstein January 27th, 2015 11:09 pm

    In theory (!), Stefan, DIN settings are DIN settings. You answer the questions and, using your answers, look up the settings on the standard DIN table. That’s what I did for my Vipecs. Then I subtracted 0.5 from each value for good luck, since I seldom release for cause, and have never pre-released from AT bindings. I’m the guy (kid at the time) who can’t remember pre-releasing from his Cubco bindings. Maybe I just have a memory problem.

  165. Rick Howell January 28th, 2015 7:11 am

    In practice, Stefan — the binding is one component of the ski-boot-binding system (SBB-system). Therefore, the boot has an effect on release. This is why — after the recommended setting is selected and applied to the binding — it’s best to have a ski shop measure the release of the complete SBB-system so that the measured value can be compared to the binding manufacturer’s recommended range of release tolerances for the full SBB-system. If the measured valued falls within the range — it’s time to ski. If the measured valued is outside of the range, then the binding manufacturer’s troubleshooting procedures should be followed to bring the measured release values to within the range, then ski. If after following all of the recommended troubleshooting procedures, the measured values continue to fall outside of the range, don’t ski on the system as it is: the boot and/or the new binding are too-worn or defective and should be retired from use or returned to the boot or binding company for replacement under warranty — then the full SBB-system should be re-tested by the ski shop, again.

    Typical measurements in this way are common among ski shops and release measurements by a ski shop are useful with any binding that provides lateral toe release, such as yours. If your nearest ski shop cannot provide this typical service, I can recommend one that can — if you could please let us know the region in Mass where you live.

    (( Bindings that do NOT have lateral toe release encounter the issues noted in the graphs at the top of the article — thus rendering ski-shop measurement of lateral release moot.

    Forward release measurements (force or torque) and the subsequent troubleshooting service performed by a ski shop are (somewhat) valid with any releaseable binding.

    Utilizing ski shop release test equipment to provide lateral release FORCE to the heel of a boot that’s used in conjunction with a binding that does NOT have lateral toe release will provide false-positive information (please see above ‘force’ graphs): that false-positive information will not be useful in conjunction with the binding manufacturer’s recommended release testing procedures.

    The same applies to ski-shop measurement of torsional-TORQUE for bindings that do NOT have lateral toe release: the information derived is a false-positive (see above release ‘torque’ graphs). ))

    Ski shop release testing of the complete SBB-system involving bindings with lateral toe release and all bindings with forward release capability is not mandatory in the US, but it’s “recommended” by all responsible binding companies — and it’s highly recommended by me.

  166. Rick Howell January 28th, 2015 9:05 am

    @ Bruno: Here’s my response to your two good questions about binding design.

    Functional decoupling for release and retention: This form of decoupling is relative to a 6-degree-of-freedom spatial coordinate system at every moving interface within the complete ski-boot-binding-LEG system. Some degree-modes should be decoupled from others, some should not: the choice (in binding design) depends upon the overall basics of skiing technique.

    Decoupling — or in the alternative, cross-linking — should be intentionally applied to binding design relative to the interaction of each ‘degree-mode’ within the six degree-of-freedom coordinate system. In a robust binding design, some of these modes should be release modes, the others should be retention modes. Unwanted cross-linking becomes apparent when the ski and boot begin to separate during controlled skiing. Desirable decoupling is apparent when the ski and boot are united during controlled skiing, but release in the presence of injury-producing loads. In practice, there’s always a touch of cross-linking on a micro-scale. The macro-scale that applies here is the ‘release’ or ‘retain’ option. Retention is linked to skiing-control.

    The 6 degrees-of-freedom coordinate system includes 3 rotary and 3 translational modes. They are pitch, roll, yaw, lateral shear, fore-and-aft shear and vertical (up and down) shear.

    In skiing, should the inducement of a roll load (proper edging) cause lateral movement (or, lateral release — toe or heel)? No. There’s no biomechanical need to provide roll release — but providing a super stiff coupling in the roll mode is outstanding for skiing-control. But we need lateral toe release to maintain tibia integrity and lateral heel release to maintain ACL (and perhaps MCL) integrity. Therefore, a good binding’s design should decouple roll from lateral. Spademan did not. (Jim’s Cubco did not provide functional-decoupling between roll and lateral in the toe, but it did in the heel.)

    Should the inducement of forward shear loading cause lateral toe movement (or, lateral release — toe or heel)? No. There’s no biomechanical need to provide forward shear release — but providing blocked forward shear movement is essential for skiing-control.

    And so forth …….

    A matrix can be constructed with all 6-degrees-of-freedom pertaining to release along one axis; while the other axis contains all 6 pertaining to retention — then make a binary decision at each interaction.

    The fun part involves a 3rd matrix-dimension for the interaction of ‘toe’ or ‘heel’ that leads directly to your second question.

    When a ‘lateral, controlled-skiing load’ (at a load-level that is non-injurious) is applied to a ski that’s free in 5 degrees-of-freedom (the 1 un-free degree is the applied lateral load), while the boot is fixed in all 6 degrees (you’re skiing in a non-injurious moment), will the toe AND heel release inadvertently (pre-release)? In my binding design, the answer is no. Resoundingly and decisively NO. The reason is because there is no biomechanical need for BOTH the toe and the heel to release simultaneously in the presence of innocuous lateral loading. Lateral toe-only addresses tibia; lateral heel-only addresses valgus-domanent ACL — and besides, by definition, in controlled skiing, the loads within your ‘good’ skiing technique are applied between the ski and the boot at levels that are below the fracture-limit of the tibia and the ACL.

    From a ‘purely binding perspective’, simultaneous lateral toe and lateral heel release requires the SUM of both the lateral toe release force AND the lateral heel release force: overcoming the sum of both is far beyond the limits of either limit alone. Further, if the applied lateral load shifts slightly forward or slightly aftward on ski (as during a ‘hockey stop’), Enrico Fermi’s hunt for the lowest state of ‘work’ comes into play: the kinematic path of the load that flows between the snow and the leg will automatically become the easiest path. The action (the applied load) and reaction (by the SBB-leg system) will hunt to the lowest amount of work. This ‘work’ is a product of the release force supplied by either the toe OR the heel AND the lever-arm formed between the point of application of the applied load and the binding’s natural pivot-point (lateral toe release relies on a natural pivot formed near the heel; lateral heel release relies on a natural pivot formed near the toe). Under this condition — a slightly shifted point of applied lateral loading (which occurs every millisecond while skiing) — the resistance that’s supplied by the binding will hunt to either the toe OR the heel, not both. At this point, the toe or the heel will provide retention based on the selected release levels.

    This is why, in a strict sense, release AND retention are in fact cross-linked (not decoupled) within a given mode OF RELEASE (but there’s a load-limit within each mode) … but the best binding design intentionally decouples skiing-control-loads loads from injurious-loads that are flowing BETWEEN the various 6-modes — selectively — to avert ‘summing’ undesired cross-linked loads that would cause pre-release.

    The full interaction matrix is described in the utility patents that have issued for Howell-invented ski bindings (and for Howell-invented clipless bicycle pedals: I invented the 1st hands-off clipless bicycle pedals based on functional-decoupling).

    In view of this information, consider the decoupling or cross-linking interactions between all 6 degrees-of-freedom for both release and retention when consider the design of pintech bindings.

  167. Stefan January 28th, 2015 9:13 am

    So I guess I was right thinking this was too complicated for me. Rick does make it sound intimidating and it would seem just turning the screw to the right number is inadequate .Who in mass knows about this stuff, and has the equipment to adjust it?

  168. Rick Howell January 28th, 2015 9:26 am

    Hi Stefan, All ski shops since the late 1970’s should have ski-binding release measuring equipment and be trained to use if per the binding manufacturers’ training programs and per the release testing equipment manufacturers’ training programs. Come to think about it — I can’t think of one ski shop that services bindings with lateral toe release (that’s all alpine bindings) that does not provide measurement of ski-binding release.

    Many ski shops have high school kids who are well trained on this topic that provide outstanding service in this way. It’s simple and straightforward with the normal training that’s supplied to all ski shops that service toes that provide lateral toe release.

    The only ‘complicated’ part is for other skiers who use bindings that do not have lateral toe release: they should suggest to their ski shop that lateral (or torsional) ski shop release measurement is moot for their bindings because of what’s shown in the graphs above. That suggestion by skiers to ski shops does not apply to you.

    Rick Howell
    Stowe, Vermont

  169. Rick Howell January 28th, 2015 9:29 am

    Typo correction: should read: “All ski shops since the late 1970’s should have ski-binding release measuring equipment and be trained to use it per the binding manufacturers’ training programs and per the release testing equipment manufacturers’ training programs.”

  170. Stefan January 28th, 2015 9:57 am

    So where do you work rick? Nordic barn?

  171. Rick Howell January 28th, 2015 10:20 am

    Stefan, I am an owner of 2 ski binding companies.

  172. See January 28th, 2015 10:22 am

    I don’t claim to understand a lot of the technical information Rick has shared, although I look forward to reading his comments more carefully when I have time (thanks again, Rick). I do, however, think that there is some value in testing lateral release on tech bindings (obviously not by applying force at the boot toe) with whatever equipment is available, even if that’s just a “carpet” or work bench test. Shop equipment that can provide some quantitative data could be even more useful.

    Lou has stated repeatedly that some boot/binding combinations simply don’t work right, and these should be identified before someone takes them out and skis on them. Also, as is described in the “race bindings for bc skiing post,” release values are not adjustable on some bindings, and it would probably be helpful to know roughly where one’s new equipment falls on the “kids rental bindings” to “world cup downhill” release/retention spectrum. And who knows what other anomalies routine quantifiable testing might reveal?

  173. jbo January 28th, 2015 10:42 am

    Rick & See – Some of the available release testing tools have a modified method of testing heel-release bindings. Dynafit attempts to approximate existing ISO charts numerically when using these modified tests. Of course, the resulting torques only make sense in the context of the tech binding graphs above and not the alpine graphs.

  174. Rick Howell January 28th, 2015 10:49 am

    See, As Jason’s article and the graphs above depict, measuring the release of pintech bindings will not change the fact that with most of them, the leg will fracture before the binding releases — and with the fixed release bindings, there’s nothing you can do. Tweaking the boot-binding interface will not change the inherently and fundamentally flawed design deficiencies of most pintech bindings.

    Do NOT perform a self-release (as you call it, a “carpet test”) with pintech bindings, because if you perform it ‘properly’ you can break your leg.

    ( Also, rental bindings are adjusted to the same standard international release setting charts as ordinary bindings. )

  175. Rick Howell January 28th, 2015 11:02 am

    jbo: The “modified method of testing heel release-bindings” that’s being put forth by certain binding companies generates lateral release values that bear no relevance to the values that I developed when I co-authored the DIN-system, as my graphs (above) clearly point out. No ‘correction factors’ will off-set the bind-spots that skew the lateral release of the binding relative to the human tibia. The tests that are suggested by certain binding companies to measure the lateral release of a binding that does not provide lateral toe release are ‘binding-myopic’ — they do not take into consideration the torsional fracture limit of the human tibia. The so-called DIN-System does. Just look at how the release limit of a pintech binding pokes through the tibia fracture limit when loads are applied to the ski at the ‘near-ends’ of the ISO testing zone. No ‘correction factors’ in the bindings’ settings or in tweaking the boot interface will make up for this fundamental design problem. We proved this 40-years ago … and to reverse all of that know-how will cause a significant increase in tibia fractures among those who utilize bindings that do not have lateral toe release. The biomechanical testing (shown in the graphs above) clearly and decisively points out this the failure with pintech bindings.

  176. Bruno Schull January 28th, 2015 12:18 pm

    Rick–that you so much for that explanation. Learning about stuff like that–whole worlds of ideas and interactions I have never thought of–is basically one of the most gratifying things for me. As I mentioned, I’m a high school biology teacher, and it reminds of graduate work I once did at the University of Barcelona. The university has a little-known but great Ecology department, and I had the incredible luck to sign up for a class with he seemingly-innocuous name of “fundamental ecology.” I was the only student. Everybody else stayed away, because the professor had a reputation for difficult theoretical and practical work. As I foreigner, I had no idea. In the end, we enjoyed a semester-long conversation about ecology, thermodynamics, dynamic equilibrium, entropy, evolution…and so on. It was pure knowledge and exploration and learning. The essence of education–like your posts. My story has strayed from the original topic, but then again, around the same time, I started ski touring in the Catalan and Andorran Pyrenees. Like the University of Barcelona, they are little-known but amazing mountains. Thanks again, and all the best. I will follow your website and buy a binding if/when possible.

  177. Wynn Miller January 28th, 2015 2:00 pm

    So how does a pin-tech binding differ from a Cubco (besides the fact that Cubco released laterally at the toe but not the heel)?

  178. Rick Howell January 28th, 2015 3:20 pm

    @Wynn: There are night and day differences in their designs. It’s too much for me to get into the answer at this time. I’ll be able to address your good question (and the others’ good comments) next week. 🙂 Meanwhile, the skiing is totally awesome here in Stowe, Vermont at this moment. 🙂

  179. jbo January 28th, 2015 9:58 pm

    Rick – Yes the modified testing procedure has no bearing on the DIN standard or the alpine graphs, and I think people understand that at this point. However they do have relevance with respect to the graphs of the tech bindings as different settings can have different amplitudes. It still makes sense to adjust and test those according the manufacturer recommendation.

    On the flip side, as you’ve pointed out, it makes no sense to adjust and test alpine bindings in an attempt to protect your ACL.

  180. Rick Howell January 29th, 2015 2:37 am

    Jbo: I’ve worked together with you for a long time on this project and I’ve never ever pointed out what you’ve suggested. ALL alpine binding companies expressly disclaim that their bindings cannot mitigate knee injuries — EXCEPT the 2 alpine binding companies that provide lateral heel release, both of which 2 companies I am an owner. I’ve stood before the entire skiing safety community several times with my full suite of research to back-up this claim — and the biomechanical proof is now before us that lateral heel release does address ACL-strain mitigation.

    I’m still working on the ‘amplitude corrections’ for pintech bindings — but, unfortunately, the results appear to eliminate a wide range of skiers: the downward corrections to off-set tibia fractures will cause pre-release. Testing lateral heel release with the implication that it’s biomechanically-equivalent to testing lateral toe release (as some binding manufacturers and test equipment providers seem to suggest) is not entirely transparent — as the graphs clearly show.

  181. See January 29th, 2015 9:47 am

    I should probably re-read this whole tome of a post before asking but, here goes anyway: Why isn’t the tech binding “no release” in the +20 cm to +30 cm valgus test (image 7) an “Oops?”

  182. Rick Howell January 29th, 2015 9:58 am

    That’s an excellent question, See. It because when lateral loads are applied to the medial edge of the ski aft of the projected axis of the tibia, internal-rotation of the femur and internal-rotation of the tibia are generated — causing ACL-strain; whereas when lateral loads are applied to the medial edge of the ski forward of the projected axis of the tibia — the polarity of rotation of the tibia inverts — causing internal-rotation of the femur but external rotation of the tibia. Internal-rotation of the femur and external-rotation of the tibia (unlike what Willick and Shea report) unwind the key anteromedial bundle of the ACL, as is reported by the vast majority of top ACL researchers … especially including Andriacchi and independently, Johnson.

  183. See January 29th, 2015 10:01 am

    Interesting, but the thought still makes my mcl’s hurt.

  184. jbo January 29th, 2015 10:38 am

    Sorry Rick, did I forget the word ‘ordinary’ again? Of course your bindings are extra-ordinary 🙂

    You posted above that “ski-binding release settings (in an ‘ordinary’ 2-mode binding) have NO correlation with ACL-injuries”. That’s all I was referring to.

    It’s possible (likely?) however, that heel-release tech binding settings do have such a correlation. Yes, as we’ve shown, there is not a biomechanical equivalence to lateral-toe release bindings, but that doesn’t mean there can be no benefit from adjusting your settings.

  185. See January 29th, 2015 10:39 am

    Further, it seems to me that binding release properties are symmetrical (one can usually use either ski on either foot) and “disturbances” can deflect the ski in either direction…

  186. Rick Howell January 30th, 2015 7:16 am

    See, Yes, lateral heel release not only produces a positive effect on ACL friendly skiing — but it also might provide MCL friendly skiing, too. This causation is still in the process of being investigated by several researchers. Skiing MCL injuries are the 2nd most frequent skiing injury (see above table in Jason Borro’s article) in terms of both prevalence and incidence: addressing MCL injury is important, too.

    All epidemiological studies show that Phantom Foot and Slip-Catch skiing injury mechanisms (which comprise ~80% of all skiing ACL-injury mechanisms) load-up only the medial edge of the ski. As noted earlier, loads applied to the front half of the medial edge of the ski do not (biomechanically) generate appreciable strain on the ACL. Therefore, to mitigate pre-release in lateral heel release mode — lateral heel release can be asymmetrical. Outward lateral heel release can be blocked to fully opt-out pre-release in the outward lateral direction, while asymmetric inward lateral heel release can actively address ACL (and possibly MCL) friendliness.

    There are other asymmetric features on some skis. Cants are one.

    Research points to fatigue as one factor contributing toward ACL-injury (amount of time skied during a day). Therefore, with this research in mind, I switch edges to have a fresh edge all day. I ski with the asymmetric lateral heel release feature in the active left-right position in the afternoon — but in the inactive right-left position in the morning. This way, I have a fresh edge all day, while the knee friendly feature is active when it’s most needed.

    Compromise is a reality.

  187. See January 30th, 2015 8:25 am

    Thanks Rick. The new binding sounds very cool. Keep the weight down and I’d definitely be interested in trying them on my resort boards.

    Re. the valgus “no release” zone around the toes of tech bindings: I was wondering if 1) although “(i)nternal-rotation of the femur and external-rotation of the tibia… unwind the key anteromedial bundle of the ACL,” the mcl might still be vulnerable to injury due to lack of release under these conditions, and 2) since lateral loads can occur in either direction (from the inside or outside/ right or left) during actual skiing, a load applied to the other side of the ski in the + 20-30 cm zone would cause the ACL to “wind up” and be vulnerable to injury. In other words, is it the case that “loads applied to the front half of the medial edge of the ski do not (biomechanically) generate appreciable strain on the ACL” regardless of whether those loads are from the inside or the outside?

    My apologies if I just don’t understand this complicated subject and my questions don’t make sense.

  188. Rick Howell January 30th, 2015 8:55 am

    See, Yes, you are right about loading the front half of the ski on the medial edge: this could interact with MCL strain. Good point.

    I’ve been too tibia and ACL myopic! Also, this is the 1st blog group that’s come to the edge of these new findings about the issues surrounding bindings (all forms of bindings — including alpine AND pintech), tibia’s and the ACL. Thank you for pulling my thinking into the MCL issue, too.

    In your 2nd point, you posit that loading-up the outside edge of the ski in front of the tibia might also produce ACL-strain. In this scenario, the kinematics would produce inward rotation of the tibia, but outward rotation of the femur. This set of leg-segment conditions unwinds the ACL. Valgus-moments are generated by the interaction of the tibia and the femur, both with internal rotation.

    (( Valgus-moments are measured as torque about the femur when knee-flexion is ~90°. Variation in knee flexion aside from ~90° requires valgus-moments to be measured as ‘lateral overturning moments’ of the tibia (as in structural engineering analysis/design of columns regarding earthquake-factors). I measure valgus-moments when knee flexion is ~90° by measuring femur-torque. Phantom-Foot ACL injuries occur when knee flexion is ~90°.

    That’s it ’till next week …. 🙂

  189. See January 30th, 2015 9:12 am

    Enjoy the snow out there in VT, Rick. If it weren’t for this Ridiculously Resilient Ridge, maybe I’d be skiing you’d be sitting at your desk. But seriously, thank you.

  190. Rick Howell January 30th, 2015 9:18 am

    … actually, I should add one more post today:

    There will be a fantastic skiing safety conference in Cortina, Italy, March 8-13. Here’s the website: []. I encourage all of you who are interested in this topic of skiing safety to attend. Presentations will be on skiing safety/injury epidemiology, biomechanics, prevention, performance-interaction, diagnosis, treatment, rehabilitation, resort safety, head injuries, equipment-factors, avalanche research — by the leaders in these fields who are from all over the world, especially from Japan, Europe, and the Americas. I’m honored be giving a presentation on: “Unified Structural Analysis of ACL and Tibia Strength for Skiing.” Early (discounted) registration ends today.

  191. Chukko February 12th, 2015 6:49 pm

    Hi Rick, thanks for the invaluable insights. I have couple of questions

    1) Applying torque on the ski shows useful data, but there might be some fall scenarios where body rotates, instead of the ski. Have you tried some reverse measurements (i.e. rotating “tibia” rod) – measuring release torque?

    2) I do understand measuring full 3d envelope is another feat, but somehow i find measuring weighted boot a bit closer to reality than unweighted one. Did you do any (e.g. sample) measurement with weighted boot and how it affected the envelope shape (or at least how much if shifted the single measurement)?

    3) It is not quite clear on individual release points – which side of the binding got released (here i assume that alpine binding with toe side release only can still release at heel (and tech at tip) – is that correct?

    4) You mention that your 2 companies are the only alpines ones with lateral heel release. I might be wrong – but several years back i was under impression that diagonal (i.e. lateral+forward) heel release is rather common – was my impression wrong?

    5) What is the situation on measuring elasticity or pre-release under dynamic load (e.g. different frequency/amplitude inputs emulating various conditions)?

  192. Rick Howell February 13th, 2015 9:08 am

    Hello Chukko,

    ‘Good questions. Here are my answers:

    1— We did not apply torque to the ski: we applied force. In response to these applied forces at various points along the length of the ski, we measured these peak loads AT SKI-BINDING RELEASE: (a) applied-force; (b) resultant tibia-torque; (c) resultant Valgus-moment (or, ‘Valgus-Torque’). The applied-force(s) were applied to various points along the length of the ski.

    In the ‘force-graphs’ (above, within Jason Borro’s article), the peak-force that took place at the moment of each ski-binding release (“each release”, means ‘each release when the applied force was applied at each point along the length of the ski’) is depicted in the vertical axis at each discrete-location along the length of the ski. These discrete peak-force-values at release (discrete, individual, separate test results) were then graphically-connected at each of their peak-values to form the ‘2D force envelope’ that’s depicted, above, in Jason’s article.

    In the ‘torque-graphs’ (again, above, in Jason’s article), the peak-torques (tibia and separately, valgus) that took place at the moment of each ski-binding release is depicted in the vertical axis at each discrete-location along the length of the ski. These discrete peak-torque-values at release (discrete, individual, separate test results) were then graphically-connected at each of their peak-values to form the ‘2D torque envelopes’ that are depicted, above, in Jason’s article.

    In view of Isaac Newton’s laws of action-and reaction — applying tibia torque into a metallic tibia that’s attached to a ski (via boots and a binding) when the ski is constrained at only one point … is exactly the same as applying a force to a ski, then measuring the resultant torque on the tibia.

    In practice, ISO 9462 Method-A induces tibia torque by rotating a metallic tibia while the ski is fixed to a bench. This is completely different. In this case, the kinematics of the metallic tibia and its accompanying applied-loading mechanism supersede the kinematics of the binding — thus providing test-device bias into what’s supposed to be a ski-binding test. This approach is fundamentally-flawed because it assumes that all binding’s cause exactly the same natural points of rotation between the boot and ski — when, in fact, as we decisively see in Jason’s article (above) all bindings do NOT have the same points of ‘natural’ rotation (thus causing variation in the ‘effective-lever-arms’) — generating radically different resultant loading onto the tibia. ISO 9462 Method-A is therefore somewhat helpful for the manufacture of bindings — but ISO 9462 Method-A provides a false-positive when it comes to the resultant loading on the tibia. ISO 9462 Method-B properly induces forces into a ski in 5-degrees-of-freedom (it’s floating, just like in the snow) — at different points along the length of the ski — then the applied peak-force is measured and the peak resultant tibia-torque and peak resultant valgus-moment are measured on the simulated metallic tibia and femur: in this way with ISO 9462 Method-B, the effect of each binding’s ‘natural’ kinematics are measured in terms of their consequences on the tibia and the ACL (“ACL”, by combining tibia-torque and valgus moments into the above-discussed simulation-algorithm). Therefore, ISO 9462 Method-B is more about how a binding effects the human; whereas ISO 9462 Method-A is more about how to manufacture a binding.

    Lastly, a full 2D-release envelope measures all possible lateral loading conditions so that hypothetical fall-scenarios involving lateral loading become moot. It is the lateral-component of a fall-vector that causes torsional tibia fracture … and that generates valgus-moments that are associated with 80% of all ACL ruptures. This approach eliminates speculation about fall-scenarios: If a certain applied load (and resultant torque) within the 2D-envelope exceeds the biomechanical limit at ski-binding release, then there might be a fall-scenario that could produce injury. Simulating biomechanical failure eliminates fall-scenario speculation.

    2— I have tested ‘combined-loading’ in my experimental ski binding testing devices extensively. As Jason notes above in his article, this work is available — but the tests involve considerably more time and expense to conduct. It is remarkable that Jason Borro has paid for the 2D tests that we see above: paying for 3D (combined-loading) tests is just too much for one skimo retailer to incur by himself. If this group within this blog can collectively organize funding for these 3D tests, I will be glad to conduct them.

    In general, combined-loading tests produce results that are worse for the tibia and for the ACL. The design parameters that effect combined-resultant-loading on the tibia and the ACL are a function of (a) friction, and (b) pivot-point-location (‘natural’ points of rotation between the ski and the boot that are driven by each bindings’ unique design).

    3— This data (lateral release at toe; OR, lateral release at heel — at each point of applied lateral loading) was generated in the test series that Jason discusses in his article — and Jason distilled this information into his text.

    4— To be clear, I am “an” owner of 2 ski binding companies, not ‘the’ owner of 2 ski bindings companies.

    So-called ‘Diagonal Release’ that’s a feature in Head / Tyrolia / Fischer / Elan alpine ski bindings ONLY provides lateral heel release AFTER the heel has lifted during forward release. Phantom Foot and Slip-Catch injury mechanisms that are associated with ~80% of all skiing ACL injuries involve REAR-weighting. During rear-weighting, the so-called ‘Diagonal Release’ that’s featured in those bindings is fully-blocked (by design) and therefore cannot and does not provide lateral heel release during rear-weighted combined-valgus loading that causes ACL injury.

    The 2 current ski-bindings that I’ve developed provide lateral toe OR lateral heel release during rear-weighted combined-valgus loading.

    5— Pre-release is caused principally by a lack of functional decoupling (please see my extensive discussion about this concept in my blog posts, above). Elasticity is a design-parameter that effects the functional-requirement of not having pre-release. ‘Elasticity’ does not have a one-to-one correlation to pre-release: “elasticity” is not a ‘functional-requirement’: it is one of several design parameters that effects pre-release. As I noted above in my posts, there were many bindings that had outstanding elasticity that pre-released extensively. Dynamic loading is one driver of pre-release.

    so, ‘yes’, measuring pre-release and developing bindings to mitigate pre-release is a Very Big Deal … but the above article discusses the release — not retention.

    Bindings with poor functional decoupling and/or poor elasticity and/or poor friction-mitigation REQUIRE high release settings in a crude (and poor) attempt to off-set bad binding design. In a good binding, retention (anti-pre-release) is controlled by binding-design, NOT by release settings.

    Rick Howell
    Stowe, Vermont USA

  193. Lou Dawson 2 February 13th, 2015 9:57 am

    Nice Rick, thanks!

  194. Rick Howell February 13th, 2015 10:16 am

    Thank you, Lou — for the opportunity to provide this information within your forum.

  195. Chukko February 13th, 2015 2:55 pm

    Hi Rick, thanks for explanations

    1) I believe i understand the measurement but wasnt very precise in expressing myself. I didnt intend to replace your measurements with tibia rotation via rod, only to complement them – or rather put those two approaches in perspective. In your scenario, you do not only rotate tibia, but you also apply lateral force to it. If you applied the same force in opposing directions on both ends of a ski at the same time – you would isolate the torsion and get rid of lateral load. I was only curious if you tried to compare the result of torsion alone with your results (and i do not mean complete set, just ballbark comparison). E.g. how far off are ISO 9462 results from yours for the best/worst case?

    2) Here i wasnt interested in precise reliable result – just ballpark figure – e.g. how many % did the weight add to the measured release torque? Was it in closer to 10% or 50%?

    3) I read whole article and the discussion – i may have missed something. I’ll try to reread more thoroughly. I meant just quick yes/no answer (whether it was always the lateral release end (toe for alpine, rear for tech) which got released no matter which end of ski was loaded)?

    4) Understood. It is rather alarming that awareness of this topic is so low across general population. Btw havent you considered producing safer tech binding? Or is that too niche a market to be worth investing time/money?

    5) I did read your explanation on elasticity and didnt want to delve deep into details, pls pardon my imprecise formulation. My qyuestion was rrahter – if there are any actual tests (either standard or devised by you) – testing the dynamic behavior of retention (except for human skiers on the snow).
    I read now the article on ISO certification – and static part was explained there.
    It might maybe a better idea to discuss this topic there.

  196. Rick Howell February 13th, 2015 5:27 pm

    Dear Chukko,

    1— I combine 2 methods in the above tests:

    1.a— One method that I utilize is, in part, ISO 9462 Method-B. This ISO standard test method provides resultant tibia-torque values as a function of the position of the applied force (ISO 9462 Method-A does not provide position dependency: position-dependency is important (see the above graphs). A lack of position-dependent data is why those who test only according to ISO 9462 Method-A cannot ‘see’ the ACL solution.

    (( BTW — I do NOT rotate the tibia: the tibia is fixed at the proximal end: the applied-loads are imputed into the ski in the form of ‘force’: torque about the tibia is measured on the tibia itself. ))

    1.b— The other method is my proprietary Valgus-moment method, where I am measuring torque about the femur when knee flexion is 90°. If knee flexion is to be simulated at different angles, then femur torque will not provide valgus-moment measurements. I am not going to discuss in this blog how valgus-moments are measured when knee-flexion is not 90°.

    1.c— I then combine the position-dependent tibia-torque (utilizing international standard test method ISO 9462 Method-B) together with my proprietary position-dependent valgus-moment test data to derive simulated experimental ACL-integrity. This approach (‘combining’) is also proprietary.

    1.d— I never apply force to the tibia. I apply force to the ski. The ski then provide a lever-arm that becomes biased against the unique leverage supplied by a given binding-design then also biased against the RATIO of the lateral toe release to the lateral heel release coupled together with the resistive structural characteristics of the tibia in order to provide static equilibrium. Equilibrium is then disrupted when the applied-load either exceeds ski-binding the release threshold OR if the leg fractures.

    Having covered these enhanced definitions of the combined test methods, I can now answer your question. Yes, I test pure-torque, too: that data is similar to the asymptote that Jason references in his article where the measured-values (forces, torques and moments approach a limit on each end of the ski).

    The entire point of these position-dependent tests is to show the folly of relying upon ‘pure-torque’ as a barometer of resultant loading on the leg: as we can see in the graphs, there is a Very Large difference between the application of pure-torque and the application of position-dependent loading on the ski. In the above graphs, one can see that when loads enter the middle third of the ski (not the ends where pure-torque provides a false-positive) — bad things happen, biomechanically.

    ISO 9462 Method-A provides pure torque measurements (only). Relying upon Method-A only for ski-binding design is (in my book) negligent.

    As to the amount ( “how far off” ): please see the graphs above to compare the asymptotes at the far right and far left ends of the graphs to the peak-values shown in the middle-third of the ski.

    The other binding companies and the other researchers have been attempting to discover why ACL strain develops with bindings by utilizing only Method-A. That’s like trying to see Pluto without a telescope.

    Finally, two of the most significant independent ski-binding biomechanical researchers are presently constructing devices that match mine to make the observations that combine method-B together with valgus-moment measurements. Unfortunately, this work should have been started by others immediately after I presented my discovery at ISSS-Japan in 2005: it will take the other researchers years to de-bug these test methods to the point where they will be able to gather meaningful data. Then, once they do start to develop meaningful data — I remain confident that they will then be able to independently validate the interactions of ski-bindings within the kinematic pathway that’s between the snow surface and the hip that cause ACL-rupture.

    2— With the best alpine bindings its approximately -5% (negative five %). Please note that the human tibia becomes WEAKER in the presence of combined torsion and bending (weighted torsional loading). The worst bindings increase more than 300%: leg fracture occurs before binding release.

    (( Please remember, weighted loading is also applied-loading ‘position-dependent’. ))

    3— ‘Lateral toe release’ OR ‘lateral heel release’ is purely-dependent upon the POSITION of the applied load onto the ski. With pintech bindings it is IMPOSSIBLE for the toe to release laterally (please see above graphs) when a lateral-load is applied to the ski near the toe. When lateral loads are applied to the ski near the toe (and the binding cannot release) a torque IS generated on the tibia — but the binding ‘feels’ zero release-loading: there is a ‘gap’ between what the leg feels and what the binding feels. This ‘reading-reacting-gap’ breaks tibia’s. With ordinary ‘step-in’ alpine bindings it is nearly-impossible to release laterally at the heel (see above graphs): in this case, there is a gap between what the binding feels and what the ACL feels. With turntable alpine bindings it is IMPOSSIBLE to release laterally at the heel (no boot can pass, laterally, through the side-lugs of a turntable): in this case there is definitely an ACL rupture. With bindings that have the capacity to release laterally at the heel OR release laterally at the toe — the logic-control is a function of (i) the position of the applied load; (ii) the ratio of the lateral heel release to lateral toe release; (iii) boot sole length.

    The answer to your important question therefore cannot be “yes” or “no”. If it was that simple (binary), the ACL problem would have been resolved decades ago.

    4— What is “safe” ?

    Presently, I’m focused on winning the 6-year, multi-million-$ litigation to win-back the assets of one of my ski-binding companies. When the litigation is completed in approximately 2-years, I will then assess your good question. Meanwhile, it is my goal to provide as much solid engineering information as possible on the important topics that surround your good questions.

    5— Yes, ISO 9465 is the international standard for testing lateral impact (“dynamic”) loading of alpine ski bindings. Several people have acquired their PhD’s on the dynamic response of ski bindings (e.g., University of California-Davis, Professor Maury Hull) both on-slope and in the lab. Maury’s PhD-dissertation chairman (at U.C. Berkeley) was Dan Mote (currently the President of the American Academy of Sciences): Dan has published extensively on the dynamic-testing of ski bindings. I can connect you with these fantastic papers.

    We binding designers do feel that ISO 9465 is strict enough: therefore, each binding company has independently-developed our own in-house, proprietary, dynamic testing protocols for both on-slope and lab-based dynamic testing (mostly coplanar to the snow-surface).

    Unfortunately, most pre-release problems with ordinary alpine bindings is in the forward-mode. I believe that I have developed the most advanced in-house test method for measuring the dynamic forward response of ski-bindings. i developed this method over a period of 40-years. Because there have been several fatalities close to me that were caused by forward pre-release (all on ‘other’ bindings) — I decided to disclose my proprietary method — and presented my laboratory forward dynamic test method at the ISSS conference that was held in San Carlos de Bariloche, Argentina 2-years ago. This presentation will be published, soon. Hopefully, this disclosure will help to reduce serious injuries that are a consequence of forward pre-release.

    Those are my thoughts, today.

    Kind regards,
    Rick Howell
    Stowe, Vermont USA

  197. Rick Howell February 13th, 2015 5:36 pm

    Important typo correction, above: Under my last point #5, it should read, “We binding designers feel that ISO 9465 is NOT strict enough. Therefore, each binding company has independently-developed our own in-house, proprietary, dynamic testing protocols for both on-slope and lab-based dynamic testing (mostly coplanar to the snow-surface).”

  198. Bruno February 17th, 2015 12:00 pm

    What is cost of the 3D study? Certainly less than my wife’s recent hospital bill ($50k), loss of work and (more importantly) play, and pain and suffering after experiencing a spiral tib-fib.

  199. Rick Howell February 17th, 2015 1:40 pm

    Dear Bruno,
    ‘Very sorry to learn of your wife’s injury.
    The cost of a 3D study should be negotiated by you & me, privately. I can be reached in that way at .
    Rick Howell
    Stowe, Vermont USA

  200. Rick Howell February 17th, 2015 1:42 pm
  201. Rick Howell February 18th, 2015 1:11 am

    3D envelope testing — 2 options:

    Option-A: All of the above 2D test results (peak applied abduction force; peak resultant tibia-torque; peak resultant valgus-moment); PLUS vertical pre-load (weighted ski) — as a function of position of applied-force = US$7000 / binding.

    Option-B: All of the above 2D test results (peak applied abduction force; peak resultant tibia-torque; peak resultant valgus-moment); PLUS peak resultant forward release (combined with above); PLUS peak resultant backward release (combined with above) (‘weighted-ski’ included) — as a function of position of applied-force = US$19,000 / binding.

  202. Lindahl October 7th, 2015 6:36 am

    I’d love to see an updated graph withthe testing of Dynafit Radical 2.0 design with the rotating toe. I wonder if this design yoelds superior release torques for both ACL (vs alpine) and tibia fx (vs tech).

    Last year I had a relatively minor fall which plunged the ski tip vertically into the snowpack, no release and a major ankle sprain that took me out for months. Pretty sure the non-release fell into the region shown in the graphs for tech bindings and I’m wondering if the 2.0 design with the rotating toe would have prevented injury.


  203. Rick Howell October 7th, 2015 7:41 am

    @Lindahl: Respectfully — please pull together the necessary funding (please see above) — and I’ll be glad to provide you with the test results. Kind regards, Rick Howell, Stowe, Vermont 🙂

  204. Wynn Miller October 7th, 2015 8:34 am

    @Lindahl – as painful as it is to recall injury, would you please explain what happened during the “fall which plunged the ski tip vertically into the snowpack” ?

  205. Lou Dawson 2 October 7th, 2015 8:40 am

    Hmmm, interesting thought… in my opinion the rotating Radical 2.0 toe might make the “blind spot” smaller, but it will still exist.

    What is much more interesting to me is if the Radical 2.0 can overcome the challenge that “heel release” bindings have had for decades, that of trying to make a binding that is easy enough to release sideways at the heel, while still being elastic enough to hold you in while you’re skiing with the binding set to “normal” release torque settings.

    While the Radical 2.0 receiving TUV certification is not the answer to the question, it does give one a bit more confidence. Consumer testing will be the only real way to get a conclusion. Early adopters at the ready!

    Alpine “toe release” bindings have been successful for a reason. The major shock and turning forces you exert in modern skiing are more at the heel than the toe, so without it being able to rotate, the alpine binding heel unit can resist those forces easily. Then, if you need to twist out to preserve your leg bones, the toe opens up and you can twist out. Placing all the side (lateral, rotation) release in the heel unit might actually be safer for your knees (as is alluded to in the article above, re pintech bindings), but in my opinion the jury is out on how resistant to pre-release such a setup will be at normal release value settings, with the toe free to rotate with no resistance.

    One of the genius things in the original Fritz Barthel tech binding design is that that lateral (side) release actually occurs with resistance at BOTH toe and heel. By strengthening the toe springs a bit and adding power towers, evolved tech bindings such as Radical 1.0 and ION have pretty much eliminated accidental release when used correctly (and intact, not broken — another issue).

    Throwing a rotating toe into the mix is, radical. IMHO. But if Radical 2.0 truly works, and it has indeed been fairly well tested now by journalist and beta testers who give it a lot of thumbs up, it’ll be quite nice.

    Me, I’m 100% happy with an “evolved” tech binding that has a normal toe unit, and a lot of other backcountry skiers are probably of the same persuasion.

    Main thing with ski safety for your knees, leg bones, head, shoulders, and other body parts. Don’t make a habit of falling or running into immovable objects. Helmets and release bindings are somewhat over stated in terms of what they offer in protection.


  206. Rick Howell October 7th, 2015 8:43 am

    @Wynn Miller: Respectfully, please remember Winn (as noted above) that recollection of injurious ‘fall-mechanisms’ are proven by good scientific research to be largely conjecture. Sorry. It would be great if this were not the case because we (the ski binding industry) would have resolved the interaction between bindings and injuries long ago. However, there is engineering-hope. Sincerely. The ‘hope’ is in the form of generating release-envelopes — where all possible combinations and permutations are tested and reported. In this way, speculation on specific injury-producing falls are averted: ‘bulges’ in the envelopes point directly to blind-spots between binding-release and biomechanical failure. Full envelopes go-around fall-mechanism conjecture. (For a full description of the research that proves that Very Few skiers can accurately recollect the facts necessary to reconstruct an engineering failure analysis, pls say the word and I’ll review that solid-research paper here in this blog.)

    Rick Howell
    Stowe, Vermont

  207. Rick Howell October 7th, 2015 9:01 am

    @Lou: Respectfully, binary logic on the issue of release OR retention ended with the advent of Axiomatic Engineering that involves functional decoupling (as I discussed, above, exensively). When Axiomatic Engineering is properly deployed into a design — one can have cake and eat it too. It’s important, Lou, to note that your conjecture is based upon zero measurements. Ski bindings are all about measurements for both release AND retention. New binding designs exist today that provide BOTH lateral toe AND lateral heel release (deploying the virtues of Axiomatic Engineering) that cannot be forced to pre-release during the harshest of loading. Why would any binding company come to make with a binding that offers lateral heel release that pre-releases? Your conjecture about where the loads manifest while skiing is far, far off the mark. We ski-binding engineers have invested millions of $ over the past 30-years into MEASURING all 6 degrees-of-freedom at both the toe, the heel, and (by vector transposition) anywhere else we feel we need to explore …. and I can tell you first hand that the loads you have described above during skiing are patently incorrect. (The 6 degrees-of-freedom measurement-coordinate system are: fore-and-aft shear; lateral-shear; vertical shear; pitch; roll; and yaw). Lateral heel release without pre-release is totally available in ski bindings that have been designed under the principles of Axiomatic Design. For a thorough review of Axiomatic Engineering, please see ‘The Principles of Design’ by Nam Suh.

  208. JCoates October 7th, 2015 9:11 am


    For no other reason then to waist time on the internet, let my give my unsolicited armchair medical diagnosis: Assuming the pain was on the outside of your ankle, I bet you had a distal fibula spiral fracture. These can often be so non-displaced that they won’t show up on plain Xray. Its pretty much impossible to “sprain” your lateral ligaments in a ski boot unless you were in leather low top boots. But rotational force can twist the bone and crack it. I have seen these several times on skiers. Xrays are normal at the ER but they have pain for a few weeks and you do an MRI or CT scan and voila! The good news is that they almost always heal up well no matter how you treat them if they are that subtle in the first place.

    Where was I going with that?? Oh yeah…I suspect that tech type non-rotating bindings probably increase the risk for these types of fractures over more releasable bindings. I bet the ACL injury pattern is the same between tech and regular alpine bindings are the same. Of course this is just conjecture right now and I don’t know of any good studies on the various injury patterns between tech and alpine bindings.

    Personally, I try to ski in control and I worry more about pre-releasing than anything else when I ski steep stuff, so I still want bomber toe pieces.

  209. Rick Howell October 7th, 2015 9:23 am

    @JCotes: Sorry, but “rotational” loading does not produce “force”: it produces ‘torque’. The fundamental differences between force and torque might explain why there is a gap between what is extensively reported above in Jason Borro’s expansive article and what you have written: there (above) is the study that shows the clear and decisive differences between the release characteristics of typical pin bindings (not Diamir Vipec) and ‘ordinary’ alpine bindings relative to tibia-fracture and ACL-rupture. Additionally, many peer reviewed medical journal papers expand in great depth about the interaction between fibula fractures and ski-binding function. No ski bindings have the any remote possibility of reading and/or reacting to the unique loads that cause fibula fracture. Please take a few moments to review Jason’s blog-article (above) to traverse the interaction between binding release mechanisms, tibia fracture, and ACL-rupture.

  210. Rick Howell October 7th, 2015 9:36 am

    @JCotes (2): Regarding pre-release. Pre-release is FAR more important to avert than release. Pre-release can cause severe injury or (as Jason Borro aptly states, above) worse. It is a binding engineer’s 1st priority to design a binding to NOT pre-release … but also meeting mandatory release requirements as defined by the minimum international safety standards (the review of the minimum international safety standards in this blog are incorrect: the review comments are based upon zero comparative measurements). Again, today, none of us have to sacrifice release in order to insure retention when utilizing bindings that are engineered with Axiomatic Design. ‘Elasticity’ is only one of several design parameters that provides retention (anti-pre-release) … AND ‘elasticity’ alone will NOT provide proper retention (proper anti-pre-release) (( see Spademan )). Further, any binding that requires ‘elevated settings’ to provide proper retention (anti-pre-release) is a lousy binding design. A binding’s design provides retention: the settings provide release. Binding design that cross-link (or that do not functionally decouple) release from retention are lousy designs. At the end of the day, the signature of a good binding design is one that can be skied without pre-release at non-elevated settings. These binding functions can be MEASURED so that skiers do not have to be unwitting guinea pigs. For those who would like to see retention (anti-pre-release) data, please say the work … and I’ll provide the data here in this blog.

  211. Lou Dawson 2 October 7th, 2015 9:50 am

    Rick and all, apologies for my untrained verbiage. I’m just trying to put my real-world impressions into lay language.

    Fact of the matter when it comes to heel vs toe release is aggressive skiers really like bindings that do NOT provide rotational release tension at the heel. I’ve been told by more than one guy who’s skiing I’m awed by that bindings such as some models of Look, that have actual metal tabs on both sides of the boot sole heel, and thus allow NO possibility of boot heel sliding to side, are desirable, but instead in the case of Look have a “turntable” at the heel to reduce friction, but the release tension for side release comes from the toe unit wings. Sort of the best of both worlds. Genius, really. And quite popular over the years.

    So, my point is that if a binding does all its side release at the heel by rotating at the heel under spring tension, with no tension at the toe whatsoever, one should be cautious about how said binding would perform in terms of accidental unintended release.

    I hope that put it more succinctly.

  212. Lou Dawson 2 October 7th, 2015 9:53 am

    Rick puts it best:

    “These binding functions can be MEASURED so that skiers do not have to be unwitting guinea pigs.”

    Our rallying cry with all this should indeed be “remember Spademan.”


  213. Rick Howell October 7th, 2015 10:09 am

    @Lou: Exactly, Lou. Spademan bindings pre-released if you breathed on them. They provided the best ‘elasticity’ EVER — but they pre-released like crazy. That’s totally unacceptable. The point: ‘elasticity’ alone (Spademan) is no panacea. Functional decoupling TOGETHER with ‘elasticity’ averts pre-release. Functional decoupling is derived from Axiomatic Engineering. The real rallying cry should be to focus on the affirmative: seek new binding designs that make extensive deployment of functional decoupling AND elasticity — that do not pre-release at non-elevated settings.

  214. Rick Howell October 7th, 2015 10:26 am

    @Lou: my last post above is directed toward your comment that quotes me. I did not see your other post above your quote-post. Here is my reply to your comment, 2-posts up:

    NO. . Diametrically incorrect.

    1— All of the engineers at the major ski binding companies live and work year-around at major ski areas with real mountains and real skiing. My comments here in this blog are based on real experience while living here in Stowe, Vermont for 26-years — and before that, being 5th-ranked in the U.S. in the DH discipline of alpine ski racing (29 FIS points) and working for 8-years in senior management at a major ski binding company. My comments are real-world.

    2— There can be no (zero) ‘tension’ between a ski boot and a binding. All of the loads are compressive — NOT in tension.

    3— Most importantly, ALL turntable bindings with ‘side-lugs’ are the #1-cause of ACL ruptures. No boot can pass laterally through the side-lugs of any turntable binding. These bindings are obsolete and dangerous even though they are still openly being sold on today’s market as ‘current’ bindings. Shame on those who make, sell, or induce others to sell or use them.

    Lou — again, respectfully, when it comes to all forms of bindings — please conduct measurements or reference validated measurements before writing. I mean that respectfully in a effort for all of us to stop diffusing the myths that have permeated ski-bindings for over 40-years. All of us must come to embrace proper criteria to evaluate ski-binding performance, not conjecture.


  215. Bob October 7th, 2015 10:37 am

    When Dr. Howell refers to Axiomatic Engineering, I assume he is referring to the Knee Binding. Yes? Unfortunately, a light weight touring version of this binding does not exist so the backcountry skier is left with the decision to choice a binding with the “lowest” risk level. If something like that exists. I have wondered if anyone has played with the idea of a Vipec toe with a Dynafit heel. I would guess there are all sorts of elasticity and release issues associated with such a design.

  216. Rick Howell October 7th, 2015 10:56 am

    @Bob: I am a life-long ski-binding engineer, not a medical doctor. Yes, the pin system that you describe would provide the functions described above — but there are legal issues (involving the manufacturers) surrounding those combined components. The alpine bindings that provide the positive functions that I discuss, above, cannot be discussed by me at this time due to real-time on-going (major) litigation: the 2-week trial is scheduled to begin Nov 9 … then, hopefully, we will have a decision within 6-months to a year … at which time I might be willing to discuss brand names. In the meantime, the functional requirements that we are discussing here in this thread today are correctly framed by the design-parameters that you have written, above. Bravo to you Bob!


  217. JCoates October 7th, 2015 2:52 pm


    I understand your point–if not all the engineering that goes into it. I absolutely think there is a market for better releasable bindings in certain disciplines of the sport of skiing. For ski touring and ski mountaineering–which this website is focused on–it seems to me like we are focusing too much on the subject. I like skiing far from the resorts and hopefully other people on terrain that is often more unforgiving and where falling isn’t really a good option anyway. I want the lightest, toughest binding I can find that I know won’t fall apart on me in the middle of nowhere or pre-release on me. The less moving parts to break the better. To me that’s what makes a good “backcountry” binding. Seems like with the whole TUV race though a lot of the company’s have ignored this market.

  218. Rick Howell October 7th, 2015 3:19 pm

    Dear J,
    Skiing-control-loads and binding-durability-loads are different from loads that cause tibia-fracture and ACL as well as MCL rupture — otherwise, we would fracture our tibia’s and rupture our ACL’s and MCL’s during controlled skiing. There are a few extremely rare examples of perfectly controlled skiing where ACL’s have ruptured — and, based upon lowering the mandatory stand-height of bindings, even these rare occurrences have been mitigated. Sometimes (again, rarely) tibia’s fracture and ACL’s as well as MCL’s have ruptured due to bone and/or ligament disease (cancer) — we binding engineers cannot help that situation. However, expressly because controlled skiing loads are decisively different from the loads that cause tibia’s to fracture and ACL’s / MCL’s to rupture — engineering-solutions are 100% possible — and do exist, today. The key to the engineering solution is to provide a simple mechanism (‘simple’ in a binding is always best) that can decisively distinguish between skiing-control loads and tibia/ACL/MCL failure loads. We have known the fracture kinematics (path of motion) and magnitude-limits of the tibia for 40-years; only recently have we discovered the key kinematics and magnitude-limits of the ACL; only ‘plausible’ theories presently exist on the kinematics and magnitudes of the MCL. We have known the kinematics of controlled-skiing loads for over 30-years. Therefore, those of us who are diligent engineers have the information at hand to properly design bindings that know the difference between skiing-control-loads and tibia/ACL injury-producing loads. The difficult part is simplicity. Here is where only the Very Best engineer shine. Reduction of the mechanism’s most simple form brings about reliable durability and weight reduction. (( Sub note: the term “loads” herein = forces, torques and bending-moments. )) Market-factors do not provide enough methods for skiers to know whether binding X, Y or Z can provide the above clarity: that’s why proper kinematic-measurements provide the keys to understanding this topic. We need more labs to construct proper measuring methods — then act to test, test, test …. and report. (( In the real-world, massive testing leads to solutions. ))

  219. Rick Howell October 7th, 2015 4:54 pm


    For more information on this topic, irrespective of the type of binding — pin-tech, AT, Frame, alpine, etc — you can locate my on-line LinkedIn profile — then, at the top of the page, go to ‘Published Post’, then click one of the two links to land into the video-app with the additional information. There is a nominal payment option of $1.99 to defray video production costs. The video is 52-minutes; is configured for research orthopedic surgeons who are also engineers; and has optional English subtitles for information clarity.


  220. swissiphic October 7th, 2015 10:46 pm

    Rick; I read the above comments with fascination. I’m curious if, in an effort of pure creative thinking, the standard interface between binding and boot, i.e. alpine binding toe/heel pieces onto the extended plastic protrusions of the toe and heel of ski boots and the ‘pin in hole’ interfaces of tech bindings were eliminated and one could design front and rear of the ski boot and the binding interface from scratch, could you envisage a better connection that would enhance the features of binding safety release which you described above? Or, are the standard designs ‘good enough’ to work with for optimization of safety release? I’m thinking about this as I am currently hacking together some garage built pseudo tech bindings for ‘safe summer skiing’ and am not concerned about release but am looking at the boot binding interface from a different perspective and have some modifications in mind which I may wish to explore just for the sake of creative design practice. Questions that come to mind are: what factors influenced the width of the toe and heel protrusions of alpine ski boots and why are they those exact dimensions? Why is the material plastic and not more hard wearing metal? Why are the toe and heel units designed to be discrete units for and aft of the boot and not incorporated into a mechanism that attaches from beneath with boot designed in synergy/harmony with this perspective? etc…..

  221. Rick Howell October 8th, 2015 5:09 am

    @swissiphic: The standard dimensions for ski boots were developed in the early 1970’s by the Austrian engineer, Anton Zoder through the Austrian standards organization — “Ö-Norms”. The interface material has a specified hardness and coefficient of friction (a very low coefficient of friction), narrowing the material to good high-grade engineerng-grade resins. The use of metal at the interface can give rise to ‘galling’ during release (see all current pin-tech bindings), depending on the nature of the interfacing binding components. If the binding utilizes berillium-copper or nickle-bronze interfacing components, galling can be mitigated, but berillium copper can cause berillitis among manufacturing workers — thus leaving nickle-bronze as the best interfacing material for the binding components. (( In the alternative, the selection of non-galling metals could be inverted between binding and boot. )) Dynafit failed to standardize its pin interface soon enough … so the present assortment of boot-brands with what I like to call ‘Dynafit dimples’ is a mess: there is tremendous variation in their locations. The international standards committees on this topic are presently focused upon precisely defining the ‘dimple’ dimensions in order to reduce variation so that the binding can better interface the dimples. Presently the Diamir Vipec pin binding has the best range of adjustability to accommodate the wide range of variation — but the net load on the leg at peak release, even after being ‘properly’ adjusted, is another story.

    I will have difficulty answering your question pertaining to open blue sky in terms of toe-heel boot interface geometry and dimensions because I don’t recognize the term ‘safety’. The term ‘safety’ in my world is dangerous. In your review of my above posts, you will see that I never use that term. Therefore, I don’t know what your functional-requirement is. One should not move toward establishing design-parameters if one does not already know the functional-requirements. However, as noted above — each of the binding engineers view retention (anti-pre-release) functional requirements to hold a higher pecking-order in terms of functional-requirements than release (noting, again, that the minimum international ‘safety’ standards must be met for ‘release’), first. We view the ‘retention’ function to drive ‘safety’ (again, I don’t like that term) more so than the ‘release’ function because pre-release can cause far more severe injuries than non-release. Therefore, if the geometry of the boot interface is changed to better optimize retention (anti-pre-release) — great! However, a change like this will create a difficult commercialization problem for binding manufacturers.

    We in the industry think that the binding-interface geometry at the toe of an alpine ski boot is ‘not-bad’. We know that the binding-interface geometry at the heel of an alpine ski boot could definitely be improved: the horizontal length of the heel projection should be longer and the angle between the aft-most edge of the heel projection and the bottom of the sole should be more angled. I believe that the sole of the heel needs a so-called ‘glide-zone’ like what’s found under the ball-of-the-foot region of alpine ski boots. We know that the present sole-lug geometry in AT boots causes significant alpine binding malfunction. We know that the metal dimples in AT boots cause hugely significant alpine binding malfunction. There are definitely issues with present boot geometry and metal dimples.

    As for boot geometry that interfaces bindings without relying upon the present toe / heel interfaces (alpine or AT) — there are LITERALLY hundreds of such boot-binding structures found in issued utility patents. Hundreds. Every good binding engineer has invested years dabbling with such designs. In this way, all I can say to you today is …. good luck. 😉 If you decide to take this path, please remember that I kindly suggest that you first address the definitions for functional requirements before tackling design-parameters ……. then, test, test, test …..


  222. Wynn Miller October 21st, 2015 6:49 pm

    Dynamite now claims “The all-new, TÜV Certified Radical 2 is the first tech binding to successfully incorporate the elasticity of an alpine binding…Pivoting toe piece for optimum combating of pre-release following sudden impacts (patent pending)”
    How does a pivoting toe piece accomplish such claimed results?

  223. Rick Howell October 21st, 2015 7:00 pm

    @ Wynn Miller: … by tricky use of grammar. Their elasticity is laterally at the heel: that’s good for the ACL. There is no lateral-translation (straight-sideways displacement) at the toe (no pivot about the long-axis of the tibia. The movement at the toe is rotational, not lateral. Therefore, torque about the long-axis of the tibia remains as-discussed by Jason Borro, at the top of this thread. TÜV is simply turning the ski around backward in the ISO 9462 test-device to measure what’s happening laterally at the heel — but this approach ignores torque about the long-axis of the tibia. Grammar. The proper solution to this biomechanical opportunity is — 2 virtual pivots: one at the heel and one at the toe acting in concert with a lateral releasing toe and a lateral releasing heel … none of which allowing pre-release. Elasticity is only one aspect of retention (see above dialog about a false-positive over-reliance on elasticity, alone, for retention).

  224. Lou Dawson 2 October 21st, 2015 7:17 pm

    Wynn, I think consumer testing will tell the tale. It’s going to be a crazy winter… Lou

  225. Rick Howell October 21st, 2015 8:27 pm

    @Lou: The problem with “consumer testing” safety products is akin to what happened with Takata air-bags, GM ignition switches, OtisMed orthopaedic jigs, New England Compounding pharmaceuticals. We already know from biomechanical tests and basic engineering that bindings that do not supply a pivot (mechanical or virtual) located under or near the projected long axis of the tibia — that the leg and the binding read and react to Very different loads.

  226. Wynn Miller October 22nd, 2015 11:53 am

    Let alone Lawn Darts!

  227. Wynn Miller October 22nd, 2015 11:54 am

    Thanks, Rick

  228. Jerry P November 3rd, 2015 12:39 am

    Where can I get me a pair of them Reinhold Zoor prototypes?

  229. See November 4th, 2015 6:50 pm

    Cross a 7tm with a tech binding?

  230. Marc S November 11th, 2015 7:10 am

    The Vipec lateral toe release seems to have an interest to protect our tibias. However I am wondering what happens in case of a frontal release. Will the toe release open easily if there is some twist ? Otherwise this may end with a “twisted knee”!
    The Vipec is different from an alpine binding in which the shoe is free as soon as one of the releases is triggered.

  231. Lou Dawson 2 November 11th, 2015 7:37 am

    Marc, one does wonder, “blocked” sideways release seems to be common to all tech bindings, though ones that release to the side at the toe have a bit less of such behavior…. IANAE

  232. Rick Howell November 11th, 2015 7:42 am

    @ Marc S: You are correct. Once the heel releases in the event of an injurious forward loading event, the toe remains closed. ( We call “frontal”, ‘forward’. ) Again, you are correct.

  233. Rick Howell November 11th, 2015 7:47 am

    @Lou: One does not need to “wonder” if one conducts testing — especially testing with measurements. As I have offered to you, previously, I will be glad to host you here at my biomechanics lab in Stowe, Vermont where tests are conducted not only in my biomechanics lab where measurement tests are conducted — but also together with on-snow testing here in the Green Mountains — expressly to eliminate the conjecture that you reference.

  234. Lou Dawson 2 November 11th, 2015 8:49 am

    Hi Rick, I always appreciate the offer, I’m always keeping it in mind. Thanks, Lou

  235. Marc S November 11th, 2015 9:36 am

    I would participate (kickstarter …)

  236. Rick Howell November 11th, 2015 10:13 am

    @Marc, If you pull together the funding, I will perform the tests.

  237. Kristian November 11th, 2015 10:39 am

    I would also participate.

    Several years ago, I was on the summit of North Diamond Peak off of Cameron Pass. I was barely drifting forward and watching my friends skiing down to the right side of me. A rare slow backwards fall occurred and I heard my left ACL pop. Of course no binding release in that situation.

    Excruciating pain. With darkness coming and bitter cold temps, I ended up wrapping my left leg with both climbing skins to stabilize it and post holed all the way back to Cameron Pass. It was impossible for me to ski. So yes, I have personally been on the bad receiving end of AT bindings.

  238. Lou Dawson 2 November 11th, 2015 11:02 am

    Hi Kristian, sorry to hear that, did you get 100% rehab?

    For the knowledge base, can you relate what bindings brand/model, and what your release settings were in relation to chart recommended settings?

    Thanks, Lou

  239. Rick Howell November 11th, 2015 11:12 am

    @Lou, Ordinary release settings have NOTHING to do with ACL-injuries: please see Jason Borro’s article (above). This fact is proven both epidemiologically and biomechanically by many ski-injury researchers, independent epidemiologists and independent biomechanical researchers. Also, release settings on AT bindings have NOTHING to do with the peak torque on the leg at release (both torsional-torque and bending-torque): please see Jason Borro’s article (above). ACL injuries pertain to the kinematics of the loading (#1, MOSTLY valgus; #2, rear-weighting; #3, tiny amount of torsion about the tibia) PLUS a specific peak-mixture (ratio) of those loads: please see Jason Borro’s article (above).

  240. Kristian November 11th, 2015 11:38 am

    So, I must admit that I was skiing home built frankenstein boots based on Scarpa Tambos and Silvretta Easy Go 505s. They were correctly set and tested. But of course there is no toe release in a backwards slow fall and I suspect the same would hold true for tech bindings.

    (I have been through the entire evolution, first skiing Mt. Washington in flimsy 3 pins… Silvretta, Ramer, Silvretta, Dynafit)

    My knee was a disaster for a couple of years, extensive re-hab, etc. Could only cycle. Then one night in the dark I stumbled over a silly house cat and jammed my leg and knee stopping an impending fall. Been great ever since and many weekends I am doing fourteeners in Colorado.

  241. Lou Dawson 2 November 11th, 2015 12:00 pm

    Hi Kristen, yes, any of the Silvretta bindings with wire toe bail had zero side release at toe, totally blocked. The heel release of such bindings was not that impressive either, most serious skiers tended to set it high. I stretched a knee ligament on Silvretta 404, just like you I was just standing there in the powder and stumbled. Luckily no tear. Lou

  242. Rick Howell November 11th, 2015 12:25 pm


    Vertical toe release and/or multi-directional toe release will address BIAD (Boot-Induced-Anterior-Drawer) skiing ACL-injury mechanisms, which comprise ~8 to ~10% of all skiing-ACL injuries. In this injury mechanism rear-weighting is greater than valgus, and/or significantly greater than torsional torque about the tibia.

    None of the above bindings have vertical or multi-directional toe release.

    Lateral heel release addresses valgus-dominant skiing-ACL injury mechanisms (Phantom Foot and Slip-Catch — which comprise ~80% of all skiing-ACL injuries) where rear weighting is less than valgus; and rear-weighting is far less than torsion about the tibia.

    Again, as noted in Jason Borro’s article, above — a discrete COMBINATION of valgus; rear-weighting; and tibia-torque are needed to cause ACL-rupture. Any binding with lateral heel release must be expressly tuned to provide release below the critical COMBINATION of these 3-loads.

    As noted here — the BIAD injury mechanism that causes 8% of all skiing-ACL injuries is a completely different skiing-ACL injury mechanism as compared to the Phantom Foot / Slip-Catch injury mechanisms that are associated with ~80% of all skiing ACL-injuries. Thus, these 2 very different ACL-injury mechanisms require 2 very different types ski-binding mechanisms to address ACL-injury mitigation.


  243. Rick Howell November 11th, 2015 12:34 pm

    Typo correction in my 3rd paragraph above: it should properly read:

    “Lateral heel release addresses valgus-dominant skiing-ACL injury mechanisms (Phantom Foot and Slip-Catch — which comprise ~80% of all skiing-ACL injuries) where rear weighting is less than valgus; and where torsion about the tibia is far less than rear-weighting and far less than valgus.”

    Thank you for your patience with me on this important correction. (smile)

  244. See November 11th, 2015 7:04 pm

    So, in my experience, a Dynafit toe releases very easily (if unlocked) once the heel is disengaged. Is this not the case with the Vipec?

  245. See November 11th, 2015 7:19 pm

    (Same question as Marc asked, I think, but I was unable to detect an answer.)

  246. Jim Milstein November 11th, 2015 8:25 pm

    See, the Vipec toe is released when the boot toe presses the front lever down after the heel releases. Once the boot heel is rising on release, leverage for lateral release at the toe is progressively lost. So, yes, the knee can be tweaked in a forward then twisting fall, despite a heel release.

    Don’t fall.

  247. Mark L November 11th, 2015 8:28 pm

    So create a frankenbinding with a Vipec toe piece and a Kingpin heel and you’re golden!

    Seriously, if lateral release at both heel and toe results in a safer touring binding (wrt ACL injuries) then why hasn’t Dynafit, Market, or Fritchi developed it? Kneebinding has been marketing such a binding for alpine for several years so clearly the technology exists.

  248. Mark Worley November 11th, 2015 9:01 pm

    I actually hucked some fairly big jumps in Silvretta 303s, and skied them a couple times with welted leather boots with no injuries, but the release they have is notably rudimentary even to the somewhat-trained eye.

  249. Rick Howell November 12th, 2015 4:01 am

    @Jim Milstein: Biomechanically — based upon loading kinematics — during injury-producing forward-twisting events, the tibia will (typically) fracture before any ligaments in the knee become ruptured.

  250. Rick Howell November 12th, 2015 4:23 am

    @Jim Milstein: …. that’s only if the binding does not release the ski from the boot.

  251. See November 12th, 2015 8:49 am

    Thanks Jim. I’ve done some searching, but haven’t found a good demonstration of how the Vipec toe releases following a heel release. Any estimates regarding how far the boot has to rotate forward before the toe releases? Is this likely to vary with boots of different shapes or worn toes? (And sorry, Rick. I see that you did provide an answer to the original question. I just didn’t understand it.)

    I admit I haven’t been following all the latest binding news, but winter is coming and the Vipec is the new design that intrigues me most.

  252. Jim Milstein November 12th, 2015 9:22 am

    Rick, glad to hear that a mere spiral fracture of the tibia would result, not a dreaded knee tweak.

    See, the Vipec’s forward toe release depends on the geometry of the boot toe and the Vipec toe lever, both of which can be altered. When the toe lever is put in Walk mode, that forward release is locked out. When traversing a steep icy slope uphill, you definitely want the toe to be in Walk mode. If the downhill ski slips down and backward, you don’t want it to release. No, no, no. Otherwise, it is unnecessary to be in Walk mode for the uphills with Vipecs.

    Gotta go. The snow calls.

  253. See November 12th, 2015 6:29 pm

    Thanks again, Jim. I found more information re. this issue at the Diamir site (duh): (“Frontal release” section). Also the “Check compatibility touring ski boots” video here: (“Toe”). It look like the boot rotates forward through an arc of about 90 degrees before the toe releases. I’m a little less psyched to replace my Verticals.

  254. Jim Milstein November 13th, 2015 9:04 am

    For me, the great virtue of the Vipec is the ease of mode change on the hoof. That the Vipec will release while climbing, when you are swept away in a slide, is the second best feature.

    As for “safety” (the quotes are for you, Rick) release, my general practice and advice is not to fall. No fall, no harm. Skiing can be fun even without falling, though many disagree. I find facial lacerations from close encounters of the dendritic sort are good enough.

  255. Marc S November 13th, 2015 2:56 pm

    This is really a great thread. Thanks to all contributors !

    I intended to mount Vipecs on my new backcountry skis because it has lateral release at the toe. I learned here that this feature should better protects the tibia from dangerous torques.
    However the article above also shows that the lack of lateral heel release will probably increase the risk of knee ligament damage compared to other tech bindings. This is really a problem because torn ligaments is clearly the main injury among ski-tourer and ski mountaineer in my circle (using mainly Dynafits), by far more common than tibia fracture.

    So my focus shifted to lateral-heel release tech bindings that have a good pre-release behaviour so they can be used at normal settings. Radical 2.0 seems to be among them with its added lateral “elasticity” ? Any other suggestion with more tracking record ?

  256. Lou Dawson 2 November 13th, 2015 3:28 pm

    Hi Marc, glad you enjoyed the “mega thread.” The problem is that this year is really “year one” of the bindings. We finally have a vast variety of most probably excellent bindings with the bugs worked out. Problem is that this is virtually “year one” as so many of the bindings had problems last year or were so new as to not get much of a track record. Also, in my experience very few people ski their backcountry bindings at chart release settings, so their testimony and experience has no significance on the pre-release vs normal settings. It is unknown at this time how Radical 2 will behave in terms of pre-release vs “normal” DIN release value settings. I suspect it will fine as they’ve been quite extensively tested. But lots of consumer testing needs to ensue. Another option is to go more traditional yet highly engineered with any of the ION options, and the Kingpin seems to be really doing well. Also, if you’re an experienced skier who doesn’t fall often, any of the hundreds of traditional design tech bindings can still be a good bet.

  257. See November 13th, 2015 6:02 pm

    One problem with the very sound advice— don’t fall— is that it’s impossible to follow if you consider the big picture. I rarely fall these days, but it took a fair bit of falling to get where I am now.

    There are a lot of different bindings on the market, each with it’s advantages, disadvantages and idiosyncrasies, so it’s really important to know your bindings and ski accordingly (in my opinion). That’s one reason I’m a bit bothered by marketing hype that glosses over what I believe are significant differences between alpine bindings and pin type touring bindings. But it’s also why I don’t switch bindings very often. So maybe one of the new super techs really is the holy grail and I just haven’t discovered it yet. I’m counting on Lou and the rest of you to let me know.

  258. Lou Dawson 2 November 13th, 2015 6:34 pm

    Trying. Like I said in another comment this is a HUGE winter in terms of sorting all this binding stuff out. I’ve got just about everything here at WildSnow HQ so with the help of our guest bloggers, the big test winter has commenced.

    Readers, if you ski your tech bindings at “normal” chart recommended release value settings, please be sure to chime in with results of your consumer testing after you’ve been out for numerous days. Thanks.


  259. Chris January 4th, 2016 4:01 pm

    I have an interesting recent situation that involved pre-release on one ski leading to a fall and subsequent delayed release on the other ski. I hope this information will contribute to the discussion of tech binding safety.

    I am an interm/advanced skill skier and was skiing on a current model pin-tech, heel release binding with a current model boot. I am withholding the brand because I am not sure it would be useful in this conversation since the concerns appear to be common among brands. The release settings were one number higher than recommended by the company. I did not have a shop test the true release value prior to using them.

    I was on a fairly steep, tracked up, resort run with ~20 cm of fresh snow. As I think Rick mentioned frequently happens, my recollection of the event is spotty but I do know the following. I pre-released from my downhill (left) leg during a right turn and a short distance later began to fall and my right leg failed to release before my tibia and fibula fractured. My right binding did release as I came to a stop without either ski on. Ski patrol was uber professional and nitrous oxide on the slope fortunately made my pain experience manageable.

    I type this from the couch where I have been sitting for the last 4 weeks recovering from a boot top, spiral tibia fracture (of course it has to be during one of the better early seasons we have had here in a long time). It broke into multiple pieces, the type the surgeon said he usually sees from motorcycle accidents. I have joined the titanium rod club. I also fractured my fibula near the knee.

    Moving forward I assume full responsibility for my injury, knowing that there are risks and unaccounted variables in this incredibly fun and addictive sport. I find it interesting that the two topics discussed in this thread happened to me in tandem. Had I not pre-released I would not have likely gotten into a situation where I needed to release the other foot and therefore not broken my leg in this situation. Before this happened I was not aware of concerns with pin-tech bindings and happened upon this thread when searching for other folk’s experiences.

    I think I will focus on solely using alpine bindings on the ski hill and before heading into the backcountry with the tech bindings I will have them tested and adjust the release accordingly. Of course I plan to ski cautiously and do hope the industry works towards incorporating alpine release technology where possible.

  260. Rick Howell January 4th, 2016 4:13 pm

    Hi Chris,
    So sorry to hear about your accident and injuries. ‘Trust you will heal and rehab well.

    Your post is exceptionally level headed in view of the circumstances … and as a consequence, I trust others will come to value your post.

    Meanwhile, I have conducted a significant amount of new tests on pin-bindings and have just recently shared them with Jason Borro, the principle author of the above article. Your concluding sentence is right-on the mark … and I trust that with certain influence, the pin-binding manufacturers will begin to conduct proper biomechanical tests that illuminate the full release characteristics of pin-bindings — which ‘release-characteristics’ bear little resemblance to ‘release-settings’.

    And, yes, mitigating pre-release is The Key. Doing this without the utilization of poor binding function / design and without elevated ‘release settings’ is a work of critical engineering experience that’s best derived from full-envelope testing of alpine ski bindings.

    Please stay with us in your outstanding communication on this important topic.

    Kindest regards,
    Rick Howell
    Howell Ski Bindings
    Stowe, Vermont USA

  261. Rick Howell January 4th, 2016 5:19 pm


    Hello fellow skiers,

    I did not see until just now several recent posts (above) that reference “ski-shop release testing” and “chart settings”. Please note that ALL forms of release testing equipment that are utilized by ski shops WORLDWIDE (that measure release co-planar to the snow surface) will provide ZERO information to skiers about the ‘release characteristics’ of pin-bindings that have lateral-only heel release (except manufacturing tolerances for lateral heel release). “Chart release settings” with pin-bindings that have lateral-only heel release have ZERO correlation to tibia-integrity. “Release test equipment” (force or torque) utilized by ski shops (today) and “Chart Release Settings” cannot address the biomechanical effect of lateral-only heel release … no matter what certain binding release test manufacturing companies tell your ski shops.

    Please importantly note that ski shop testing for forward release has some degree of efficacy with pin-bindings — though not completely. To have a biomechanically effective forward release, the forward-related pivot-point between the boot and ski should be located about 3 to 4 cm aft of the tip of your big toe. Otherwise, if the forward release pivot is located further forward (it is located further forward with ALL pin-bindings) the difference between what the binding ‘reads’ and ‘reacts’ to is considerably different from the bending-moment experienced by the leg. Therefore, ‘ski-shop release test equipment’ — even in in the forward-release mode — AS WELL AS “Chart Settings” pertaining to forward are no panacea toward ‘proper’ biomechanical binding function. For the facts pertaining to the data that illuminates how ‘release settings’ with pin-bindings that have lateral-only heel-release bear little correlation to ‘release characteristics’ — please see Jason Borro’s article, above.

    Respectfully submitted,

    Rick Howell
    Howell Ski Bindings
    Stowe, Vermont USA


  262. Rick Howell January 4th, 2016 5:49 pm


    ‘Last comment today for our fellow skiers —

    There is reference in a few posts above to ‘field-testing’ (on-snow testing) of bindings.

    Please note that ‘field testing’ of bindings is to be conducted by the binding manufacturers, not paying consumers — especially not by unsuspecting paying consumers. Each of the alpine binding manufacturers has invested millions of dollars in test equipment that subjects bindings to the wide range of ISO Standards as well as to proprietary and non-proprietary ‘Standard Industry Practice’ for retention and durability ….. in order to develop proper binding function BEFORE shipping any type of ski bindings to skiers.

    Yes, many of today’s pin-bindings come from mom and pop producers or are subcontracted to manufacturing companies that have no release-characteristics test equipment (minimum investment = ~ US $ 600,000), retention test equipment (min investment US $ 300,000) and/or durability test equipment and protocol (min investment US $ 500,000) … but being a mom and pop producer does not relieve one’s moral, ethical (or other) obligations to meet minimum ISO standards and to meet Standard Industry Practice.

    Proper ‘field testing’ of any kind of ski bindings BEFORE shipping bindings into the stream of commerce is the SOLE (and proper) responsibility of the binding manufacturers.

    Respectfully submitted,

    Rick Howell
    Howell Ski Bindings
    Stowe, Vermont USA


  263. dan January 23rd, 2016 11:20 am

    I thought this might be of interest to this discussion
    this is Axel Lund-Svindal’s crash at today’s downhill in Kitzbuhel. He ruptured ACL and meniscus in the right knee, according to various media reports
    Watch from about 5:00. The right ski never releases; but the forces are so high that the topsheet delaminates… no wonder the ACL broke.
    If this doesn’t prompt a re-thinking of the alpine binding I don’t know what will.

  264. Rick Howell January 23rd, 2016 12:12 pm

    @dan: Actually, there may be nothing new learned in Axel’s crash of today for the following same reasons as before:

    1– Decisive prior research proved that in almost all videos of skiing injuries, the precise instant of musculoskeletal failure is unknown. In fact, typically, there are SEVERAL points in any given video where failure might occur, individually or collectively.

    2– Almost ALL tibia fractures and ACL ruptures ALSO involve ski delamination with the non-releasing binding, unopened.

    3– IT APPEARS (maybe) that Axel’s impact just before hitting the 1st fence caused the ski to delaminate. That comment if mine is pure conjecture on my part.

    4– IT APPEARS (maybe) that Axel’s initial (and ‘classic’) ‘Slip-Catch’ event (just after he lands then begins the initiation of his turn) is the instant when he ruptured his ACL because the point of maximal lateral loading on his right ski appears to be located immediately behind his heel PLUS the added ground reaction force at that same instant is so large that even his left leg is unable to off-set the compression-loading (his butt hits the aft-section of the left ski). That ‘injury mechanism’ is classic ‘Slip Catch’. That event reinforces what we already know. Lateral heel release might have averted ALC rupture (but the release might have then been followed by any number of other possible loadings to anywhere else on his body throughout his remaining crash trajectory).

    Having raced DH near the top, myself, I can relate to what happened when Axel landed low on the line, then had to slam the initiation of the turn, while at the same time dealing with those two ripples in the snow at the beginning of the ‘Slip-Catch’ event. All of my commentary here is also pure conjecture in the absence of measuring the loads … which measurements were not taken in any WC ski race, ever, so far.

    Rick Howell
    Stowe, Vermont

  265. dan January 23rd, 2016 12:21 pm

    thanks for the answer, Rick. I understand that the mechanism is well known, I just thought that this being such a high-profile race it would have some consequences. But from what you’re saying, probably not.
    I had no idea that almost all ACL and tibia injuries are accompanied by ski delamination or fracture.

  266. Rick Howell January 23rd, 2016 4:33 pm

    To be clear, Axel’s left ski delaminated and did not release. His ACL injury was (apparently) to his right knee … and the ‘Slip-Catch’ event that he experienced at the initiation of his turn was to his right leg … though, again, there were several points during Axel’s fall trajectory where it appeared that large combined valgus-moments and tibia-torques — causing classic ACL-rupture — were applied.

  267. dan January 25th, 2016 7:14 am

    geez. I’m slapping myself right now – I think I watched that 7 times. I guess I wanted so much to see a connection between the torn ski and the torn ligament that I “saw” the right ski instead of the left one. Thanks for pointing this out!

  268. Rick Howell January 25th, 2016 7:34 am

    @ Dan. Yeah, I did the same thing the first 2 or 3 times when I watched the video, too. This ‘effect’ carries over into all forms of skiing, including backcountry.

  269. Dave Dodge October 12th, 2016 1:56 pm

    This is a very good analysis by Josh and Rick. Thanks to both of you.

    All bindings that pivot at the toe of the boot during release will not be able to reliably protect the tibia from a twisting loads. The only pin binding to escape this flaw is the Diamir-Vipec 12.

    It is due to a very simple design flaw:

    1) The twisting torque is equal to the force being applied to the ski times the distance to the measuring point.

    2) The binding measures the torque at the the toe of the boot (the pins).

    3) the leg measures the torque at the axis of the tibia.

    4) if the two axis’ (the tibial axis and the binding pivot axis) are not near each other the two torques are not equal.

    For example:

    1) if a force of 200 Newtons is applied 300mm in front of the toe, the torque that a pin binding sees is 200N x .3m = 60Nm (DIN 6)

    2) but the tibial axis is approximately 200mm further away from the 200N load

    3) so, the torque the tibia sees is 200 x (.3+.2) = 100Nm!! ( DIN10) (.2m is the approx. distance from the toe to the tibial axis)

    It gets worse.

    4) If the force is applied at 300mm behind the boot heel the torque the binding sees is 200 x (.3 +.3) = 120 Nm (DIN 12) assuming no release.

    5) the torques the leg sees is 200 x (.3+.1) 80 Nm. Again assuming no release. (.1m is the distance from the heel to the tibial axis)

    6) if the binding is set a DIN 8 then it will release with an effort (felt by the tibia) equal to DIN 5.3 (8 x 8/12)

    7) therefore, if you want the same retention as DIN 8 would give you with a conventional alpine binding you need to increase the setting on the pin binding by about 34% ((8-5.3)/8)

    8) then when a load comes into your ski at 300mm in front of the toe and your release setting is DIN10.7 (8 x 1.34) it won’t release until 178Nm (DIN 18). With the retention of a setting of DIN 8!

    Most pin binding will break before that, but good luck with that.

    The reason this design flaw perpetuates is that the binding industry and TUV measure binding performance by applying a moment (pure torque) to the boot at the tibial axis. When you apply a pure torque the pivot points don’t matter. Therefore the tests used don’t expose the problems. Most good engineers understand this but it would be career ending if they made it well known outside the industry. Shades of VW here?

    Skiers can not apply a pure torque. Literally, the only way a skier can apply a pure torque is to be harnessed below a helicopter and drilled into soft snow! Skiers always apply a force/couple. In other words, a force at a distance that produces a torque about the point of measurement plus a lateral load.

  270. Lou Dawson 2 October 12th, 2016 5:56 pm

    Thanks Dave, in my understanding you are correct insofar as the actual measurements and associated theory (theory being that the bindings would cause more broken legs). Though I’d add that the Trab TR2 also releases to the side at the toe, though it’s not fully a “tech” binding as it doesn’t have pins that insert at the heel.

    Real life, however, begs to differ. I’m not sure what’s going on but indeed we do hear of people fracturing tib/fib on tech bindings, but not nearly as often as one would expect from the engineering theory and testing results.

    What I’d like to see is engineers going beyond telling us the bindings have an ineffective release mode, to the point where you can show why more people are not snapping their leg bones due to your measurements and theory. Any guesses on that?

    Believe me, if I thought there was a problem and cover-up, I’d be the first person to rage. Problem is, my close group of skiing friends probably has more than 15,000 ski days on tech bindings, and not one tib-fib (I can recall) while on tech bindings. That includes my wife and son, and myself. Some of those people pretty much learned to ski on tech bindings.

    Of more concern IMHO, people do hurt themselves due to accidental release, which occurs for a variety of reasons. To reduce the chances of accidental release, people do set their tech bindings release values higher, indeed resulting in the excessive DINs you allude to. But weirdly enough, we still don’t see an epidemic of tib-fib fractures on tech bindings. Clearly, something else is going on.


  271. See October 12th, 2016 8:59 pm

    Probably no one is surprised to hear that I’ve got a theory: When a skier senses that a ski isn’t doing what they want it to do, they have a reflexive muscular response, which can lead to the skier actively twisting out of the binding. I don’t really understand a lot of the above discussion, or even my own theory, but I think action by the skier has something to do with the puzzle Lou describes.

  272. See October 12th, 2016 9:22 pm

    Also, in my opinion, tech binding lateral prerelease is mostly caused by the toe piece letting go (a function of toe spring stiffness), so cranking up the rv at the heel won’t help much.

  273. Dave Dodge October 13th, 2016 10:19 am

    Lou – the lack of injury might have something to do with the max release value of the binding. I know a lot alpine race bindings go to DIN 20 but the the actual release value doesn’t really change when you adjust them above about about DIN 14. Maybe the max release value of pin bindings is ~ DIN10 regardless of the setting. Do you have any experience with this?

    Also, the dangerous load situations are only when the loads are near the toe of the boot. This happens frequently but as a fall progresses the loads tend to move further towards the tip and out of the danger zone.

    However, I found this discussion from a link at tetongravity blog.
    where several skiers claimed to have had tib/fib fractures on pin bindings.

  274. Lou Dawson 2 October 13th, 2016 10:31 am

    I’ve definitely heard of tib-fib tech binding leg fractures, just so few it’s doesn’t seem significant, especially considering there was no way to check if the binding was set at reasonable release settings or even adjusted correctly.

    I do think it’s something to be aware of.

    As I’ve always said, a thousands times, tech bindings are not appropriate for everyone.


  275. Charlie Hagedorn October 13th, 2016 11:15 am

    I’m aware of three fib/ankle fractures on tech bindings (including my own). Two (at least) of them had locked toes.

  276. Lou Dawson 2 October 13th, 2016 11:49 am

    Indeed, if you’re going to lock out your lateral release, resulting injury wouldn’t really have much bearing on how well the binding safety release worked (smile).

  277. Dave Dodge October 13th, 2016 12:04 pm

    It is pretty obvious when you leave the toes lock during skiing that you are making a decision to reduce the risk of inadvertent release and accept the increased risk of a broken leg. But when you unlock them the skier should know that they are at a higher risk of a tibial fracture and inadvertent release than they probably expect.

  278. JCoates October 14th, 2016 12:14 am

    I’m not a mechanical engineer or involved in medical research but I worked at an ortho clinic specializing in knees for a bit (I’m a PA, not a surgeon) and have seen enough ski related knee injuries to form an opinion.

    My two-cents: Blaming all of these injuries on the binding is wrong. If locking your toes is so bad, how did generations of telemarkers survive intact? How come thousands of soccer players blow out their ACL every year? Was it from bad bindings? (answer: No)

    Knee injuries are based more on genetics, body shape/quad strength/flexibility, and plain old-bad luck than anything else and I am sure their are probably some medical articles buried out there somewhere to support that.

    Why do the same guys have stories about how they blew out both their knees on different occasions? Contrary to what they would have you believe, it’s less about the binding or them being a bad -ass skier and more about their knee mechanics (genetics) and quad strength/proprioception than anything else? And I am not blaming them for this idea…they were led to believe that through the ski industry and to a large extent the medical community (myself included).

    I know, this opinion will sound flippant and will upset some people who were led to believe that there was only one factor in their injuries, but it does become a sore spot after hearing it over and over. I don’t know the stats, but how many people ski every year? And how many blow out their knees? The vast majority do not–regardless of the binding they are on. However, (and this is anecdotal) it sure seems like the same population are the ones doing it over and over again. It sort of became a joke at work when I was getting a patient history for a knee injury. Me: “So, anyone else in your family have problems with their knees?” Skier: “Oh yeah, both my mom and dad were skier’s and they had torn ACL’s because they skied (or played soccer).” Me: “OK…see you next year when you blow out your other knee.”

    Ok, rant done…just don’t ask me if I think every ACL rupture should be repaired in the first place.

  279. See October 14th, 2016 7:42 am

    I’m not disagreeing with your rant (well, maybe a little). But, (based on personal experience and observation) it’s my opinion that non-releaseable teles are risky for any one not born with bullet proof knees.

  280. Lou Dawson 2 October 14th, 2016 8:23 am

    It seems to come down to some philosophical pondering. We like the thrill of skiing, not in small part because it requires some skill and has some consequences if you mess up. That’s why many of us prefer skiing or for example mountain biking to going down a water slide over and over again. But at the same time, many of us want our favorite sports to be safer, and we like to talk about knee and leg injuries and how bindings might do a better job of protecting us.

    And sure, I’ve written many times that you can blow a knee while hiking, or even tripping on the stairs. I know of at least one bad one that happened while roller blading.

    My opinion is that being on skis and falling does make it more likely you’ll blow a knee than if you don’t have your feet attached to big long lever arms. And I’d like to see all bindings do a better job of protecting us from this. But I don’t expect a ballistic sport like skiing to be entirely risk free and never result in an injury.

    More importantly, my editorial philosophy here at WildSnow is yes indeed we do focus on how to mitigate the truly tragic risks, example being avalanche deaths. Our opinion is that ski touring is worth an occasional injury but it’s not worth dying for unless you intentionally chose to participate in super high risk parts of the sport, such as European type extreme skiing or hardcore ski mountaineering, and have communicated to your loved ones and friends that that’s your life path and you’re good with it, and you hope they understand that’s the place you’ve chosen to be in the human life variety we all have our part in.


  281. Andrew Davies November 11th, 2016 7:41 am

    As a knee surgeon with personal experience of reconstructing nearly 3000 ACLs I really enjoy the debate on your excellent website. You have helped my journey from resort skier to skinning from my chalet garden to the backcountry and the haute route this spring.

    There are multiple publications on ski injuries and the majority will focus on preventable causes.
    1- lack of fitness / quads / flexibility
    2 – technique failure ie beginner vs expert where the risk flattens out at about 100 ski weeks so Lou is just about ok
    3 – alcohol consumption – fabulous Italian paper showed over 40 % of ski injuries there had alcohol above the drink-drive limit
    4 – binding settings – beginners don’t know and some ski hire shops can be unhelpful
    5 – there are huge swathes of the population who are just not cut out for athletic coordinated high demand activity – genetics

    Having said all of the above what do I tell my patients
    Don’t drink and ski
    Be very careful on chairlifts – sit at the edge so you can’t get trapped
    The moment you feel tired do not attempt one last run

    For years I used frame bindings but I have just converted to dynafit radical 2 and on some fat skis I have Kingpins. A whole season of use seems pretty good but the vertical release of the dynafit on one occasion was a real problem. Love the the light kit going up though

    Thanks for the blog – seeing 50 cm of snow in Verbier today so getting excited for my first weekend

  282. Lou Dawson 2 November 11th, 2016 8:35 am

    Thanks for stopping by Andrew!

    Sounds like the Alps are in shape this eason, eh?


  283. Dave Dodge November 14th, 2016 6:03 am

    Hi Andrew – I’m a product design engineer. I’ve been in the ski industry my entire career, and have been involved in ski safety research for 40 years. IMO this is the best source for tip on avoiding knee injuries:

    There is also a pretty strong correlation with quad/hamstring strength ratio. Ratios closer to 1:1 show reduced risk. More common ratios of 2:1 have increased risk. So tell them to build their hamstring strength.

    Pin bindings are slightly more knee friendly, but much more likely to cause a spiral tibial fracture and much more likely to have inadvertent release problem.

    There are standardized shop practises that most US ski shops follow and that are much less commonly followed in the EU. The binding settings and procedures prescribed by these standards will practically eliminate the risk of lower leg fractures. However, they will not offer any significant protection against knee injuries. Research shows that on conventional alpine bindings settings must be reduced by at least 50% to protect the knee and that setting that low will cause inadvertent releases to increase the risk of other injuries.

    There are some bindings that have kinematics that provide automatically an attenuated release when the load is on the inside edge of the tail of the ski. Such loads are known to cause most ACL ruptures (but not all).

    On lighter note: If 50% of ALL skiers in Italy are drunk then alcohol reduces the risk. Grappa bars at the top of lifts are common! 🙂

  284. Lou Dawson 2 November 14th, 2016 7:08 am

    Dave Dodge thanks for dropping by. Apologies for your comment ending up in our moderation hold, up now. Lou

  285. Brian Lindahl November 18th, 2016 4:09 pm

    Perhaps it’s inappropriate to post this link, but I’ve recently just published my review of the Vipec and I talk to an extent about the theories and experiments expressed in this blog article and its comments:

    Jason and Rick, thanks so much for the discussion, research, experiments and data! It shed some serious light on the injury I sustained two seasons ago.

  286. Pete Rotheroe February 28th, 2017 5:44 am

    Thanks for a great and very informative article. I especially liked the plots. As an engineer who changed over from Dynafit to the Fritschi Vipec after an ankle fibula fracture (Weber type B) in a twisting fall after my ski tip caught on a chunk of ice, it would be great if Rick ever had a chance to repeat these tests on the Vipec!

  287. Pete Rotheroe February 28th, 2017 5:49 am

    What would be the negative aspects (if any) of using a Vipec toepiece together with a Dynafit or other rotating heel piece? Would such a combination release too easily with side load when skiing hard pack???

  288. Lou Dawson 2 February 28th, 2017 8:33 am

    Pete, the Vipec does not allow the boot heel to move to the side, so the rotational aspect of a rotating heel would have no effect other than perhaps introducing a slight amount of unwanted lateral play at the heel due to flexing of the entire system.

    In a practical sense, the biggest problems with frankenbindings are 1.) It’s hard to know what release settings you’re really using. 2.) They usually require quite a bit of shimming to get your boot ramp angle where you’d want it.

    For fun, I’ve skied on a lot of frankenbindings. Use our site search for the word “frankenbinding.”


  289. Dave Dodge March 1st, 2017 7:19 am

    The Vipec/Dynafit frankenbinding could offer superior protection to twisting tibial fractures and superior knee injury protection but I doubt that retention would be sufficient at setting that would protect the knee.

  290. Lou Dawson 2 March 1st, 2017 7:45 am

    Dave, no, the Vipec does not allow the heel of the boot to release to the side, the boot is strongly retained in the toe pin-socket and can only release when the pin carriage at the toe slides to the side. Side release at the heel would do nothing, nada, zilch. This was obvious when I played around with using a Kingpin heel and Vipec toe. Doing so basically created a Tecton, but the Kingpin side release at heel did not function.

    The rig you propose could be effectuated by placing the Vipec on a turntable and combining with a heel such as Kingpin. But in that case, as you point out, who knows what kind of retention problems would occur if the rig was adjusted so it had normal release values.


  291. Dave Dodge March 1st, 2017 10:46 am

    I was talking about using the Vipec with a Dynafit type heel which does turn.

    How did you test the release? You can’t use a torque wrench type release check. To see things correctly you really need an ASTM 504 type release check machine.

    To see the difference you would have to apply a load to ski at various locations while holding to boot stationary. If you apply a force at about 20cm +/- behind the boot heel the Dynafit type heel would release before the Vipec if set at the same release setting.

    Depending on the relative settings there will be crossover point were the toe will release instead of the heel as you apply the load further towards the tail. Loads applied to the forebody will always cause the toe to release. It would be interesting to play around with but I wouldn’t recommend skiing on it.

    Putting the Vipec on turntable wouldn’t change things much as the leverage is so high. Think about why there is a release lockout for touring mode on Dynafit type bindings.

  292. Lou Dawson 2 March 1st, 2017 11:12 am

    Dave, I repeat, it doesn’t matter what type of heel, the boot heel can not move sideways when using a Vipec toe (until the toe unit disengages from the boot), or to look at it another way, the ski can’t move sideways relative to the heel. The toe pins are locked into the sockets, all side release happens by virtue of the Vipec toe carriage moving to the side. Get it? Again, the toe unit would have to rotate for the heel of the boot to come out to the side. The Vipec toe unit does not rotate.

    Of course, once the toe begins opens up and disengages the pins, perhaps the heel could rotate a bit, but that would be immaterial as you’d already be out of the binding.

    Believe me, I installed various rotating heel units with Vipec (classic tech and Kingpin), the above is abundantly obvious.


  293. See March 1st, 2017 11:14 am

    OK, now I’m puzzled. If the Vipec toe piece doesn’t release by having the pins cam out of the boot sockets when the boot heel is displaced laterally, I don’t see how having a heel that turns is going to allow lateral release when a force is applied 20 cm behind the boot. I thought the Vipec toe only released when the boot toe was displaced laterally or, (in the event of a vertical release), when the heel of the boot lifts up to the point where the boot toe depresses the binding toe lever.

  294. Lou Dawson 2 March 1st, 2017 11:21 am

    See, can you take an in-person look at a Vipec? The pins do NOT cam out, they release because the binding opens up when the boot toe moves to the side, by virtue of the moving carriage. It’s the “same” kind of release as you get in a normal alpine binding. Heel anchored, toe moving to the side, and yes, as you move the force back closer to the heel you get to a point where you have no practical side release, which as Rick points out is one of the things that can allow knee injury when using most alpine bindings, and could actually be somewhat protected against when using heel release tech bindings — and is what KneeBinding attempts to remedy by providing some lateral release at the heel. Lou

  295. See March 1st, 2017 11:33 am

    Yeah, that’s what I thought. (I wasn’t really that puzzled). For what it’s worth, I’ve had shop personnel “correct” me when I mentioned Vipec toe not releasing unless it was displaced to the side. This may be a common misconception (unless I totally misunderstand how the Vipec works, which is not impossible).

  296. Dave Dodge March 2nd, 2017 7:01 am

    How do you step into a Vipec toe then? How does a Dynafit pin cam out as the heel moves? IThe pin holding mechanism does not go over center in either as far as I know. Maybe I’m wrong though.

  297. See March 2nd, 2017 8:53 am

    Dynafits (to my understanding) use springs to press the pins into the boot toe sockets in ski mode. When the rotating heel allows the boot to twist, the taper of the toe pin overcomes the spring pressure and the pin rides up over the edge of the socket and releases the boot. I haven’t skied Vipecs, but my understanding is that the toe arms are part of a mechanism that slides side to side with the pins fully engaged with the boot sockets until it reaches a certain displacement from center, at which point an arm releases, freeing the boot. Until Lou, or someone else takes apart a binding and shows us pictures, I can only guess about the mechanism that enables all this (and the step-in function) to work.

    If the sliding parts of the Vipec toe didn’t bind up, it seems like a rotating heel could maybe allow the whole ski to get displaced to the side of the boot and release when a lateral force was applied to the ski, but I suspect that wouldn’t work in practice.

  298. Lou Dawson 2 March 2nd, 2017 10:24 am

    See, exactly, classic tech binding toe pins and boot sockets work as a “ball and socket” joint that allows the boot heel to displace to the side as the pins ride up out of the sockets due to the spring loaded toe wings opening up. Vipec does not do that. Instead, the Vipec toe carriage slides to the side, eventually opening up, but the heel of the boot can’t move to the side until the safety release is already occurring. If you can look at a Vipec with a boot in it, say at a ski shop, this is obvious in the first 10 seconds of examination. Lou

  299. Dave Dodge March 2nd, 2017 12:19 pm

    Ok. I understand all that but if entry/exit is the same as a Dynafit the the clamping does not go overcenter and the toe pins can still be pried open. I’ll have to take a closer to to see if this the case.

  300. Dave Dodge March 2nd, 2017 12:31 pm

    Yes, I understand all that but what I don’t understand is how the mechanism allows entry and exit and whether it goes overcenter when closed. Unlike the Dynafit that does not go overcenter when closed and must be locked with a cam for touring mode.

    You’re probably right Lou because if it did not go overcenter it would need a locking mechanism for touring mode.

  301. Arne March 15th, 2017 8:58 am

    Hi Lou,

    There is some related information in this video which is very interesting. One point that was a shocker for me is that his research shows that frame touring bindings are not safe to use with touring boots. They are particularly bad in combination with tech inserts, but even without they do not seem to be safe. Perhaps you can consider a follow-up article where you discuss these findings?


  302. See March 15th, 2017 10:05 am

    I thought his comment at 23:30 was particularly interesting.

  303. Arne March 15th, 2017 12:55 pm

    Thanks See, I should have checked more carefully. Yes, I agree that 23:30 was very interesting. 25:00 was also interesting.

  304. Dave Dodge March 15th, 2017 1:43 pm

    I know Jeff. His research is very good. If he says moving AFD’s don’t work with traditional AT boots I’ll take his word for it. There are solutions though. The Solomon “Walk to Ride’ sole and the Marker “Grip Walk” sole offer some of the benefits of an AT sole and work well with certain special Alpine and frame type AT bindings.

    AT boots in alpine or frame type AT bindings appear to be a no go according to Jeff. But, AT boots in tech/pin type bindings are also problematic. So, I wish he’d touched on the kinematic flaw of tech/pin type bindings that pivot at the toe and release a the heel. In other words, all tech/pin type AT bindings except the Fritschi Vipec. I know he is aware of the problem. IMO this will become a big problem as more and more unaware people ski in bounds alpine on tech/pin type bindings. I see them every day where I ski.

  305. Russell McGinnis September 13th, 2017 9:02 pm

    With all that being said above about tech bindings Alpine bindings and releasing testing. What would you say the safest tech binding is on the market today in your opinion based on your experience? Am I better off with a Fritschi Tecton over a G3 Ion 12 or Kingpin. Would you feel comfortable riding tech bindings at a resort over Alpine bindings?

  306. David Dodge September 14th, 2017 9:25 am

    Theoretically the twist release characteristics of the Fritschi Tecton and Vipec 12 are as good as any Alpine binding and way better than all other pin/tech bindings. If the actual function, forward release and durability are as good as a good Alpine binding they would appear to be great “one quiver” bindings. That being said, I don’t have personal experience with them and they are quite new to the market. So time will tell.

  307. Lou Dawson 2 September 14th, 2017 9:29 am

    Hi Russell, over and over again I’ve written that I’d advise folks, if possible, to use alpine bindings for lift served alpine skiing. That said, many skiers do use tech bindings for lift skiing. Doing so is in many cases not as “safe” as using properly adjusted alpine bindings, but most people get away with it.

    The words “safest” and “safety” are terms of art that have to have specific definitions before they stand up to much discussion, for example, a binding might simply be more safe in avalanche terrain because it has a ski brake, as opposed to another binding that does not and is used with leashes. Or, perhaps speed and simplicity are necessary for a safer attempt on an mountaineering objective. In that case, the minimalist binding might be “safer” than lugging around an enormous freeride binding.

    Even calling one binding “safest” for skiing on the lift served is subject to qualification. For example, perhaps you’ve ripped out a knee 3 times and a 4th time would possibly cripple you. In that case, in my opinion you’d be better off running a classic tech binding with careful release value adjustment. Or perhaps you’re a hard charging aggressive freerider, in that case a binding that releases to the side at the toe and supplies a stable heel unit might be “safer” due to more resistance to accidental release to the side at the heel.

    Adding to the confusion, to the best of my knowledge there have been no epidemiological studies on leg injury rates with different types or models of tech bindings, so manufacturer claims of “safety” are rather specious.

    So, as for me, I have no opinion on what the “safest” tech binding is.


  308. Russell McGinnis September 15th, 2017 6:30 am

    Hey Lou and David!

    Thanks for the long responses.

    So my qualifications for a safe binding is one that releases predictably. The way that I see it is most tech bindings will fail to release in most falling situations due to the rotating heel unit being the first point that needs to release before the entire boot can start to come out.

    Let’s think about the G3 Ion 12 in comparison to the Fritschi Tecton and a full frame AT Binding . Assuming we have the correct boot choice AT or Alpine sole for each respective binding.

    Now let’s think about three common release situations.

    1. Double ejection – skiier gets thrown off balance forward and releases at the heel. In this case the G3 would not successfully eject the skiier from the binding because unless they tweak the toe it has no mechanism like an Alpine binding to come out of toe easily. The Fritschi Tecton does have an added safety feature that theoretically the boot will hit in a forward release but If there is snow packed or ice under that lever I could see how it would fail.

    2. Catch an edge in Powder. We are skiing powder right?
    This could be dangerous for skiiers because of the tweaking the knee. The tecton should release and AT full frame as well. G3 won’t.

    I’m not picking in G3 this applies to Dynafits as well. I think that there aren’t enough safety features in traditional tech setups.

    In my opinion full frame AT bindings are still the best choice. I’m not sure why anybody would want to sacrifice safety in the back-country. I’m trying to turn myself on to a tech setup but it’s becoming more difficult the more I think about it from a practical perspective.

    It would be great to hear someones point of view using tech bindings and having to release from them in various situations.

  309. Bruno Schull September 15th, 2017 7:00 am

    Hi Russel. Search for the article about tech binding release testing. There is a very long and interesting comments section. I think it was sponsored by Cripple Creek, and involved Rick Howell. In any case, as to your release situation 2 above, it seems that tech bindings might actually protect knee tendons better than alpine bindings, in some kinds of falls, particularly those that can injure the ACL. The reasoning behind this can be shown in testing, but as Lou and others remind us, the epidemiological data is missing. In any case, it’s much more complicated than saying that AT frame or alpine bindings are safer than tech bindings. Check out that post….

  310. Bruno Schull September 15th, 2017 7:04 am

    Hi Russel (again). I realize that you were actually commenting on the very thread I recommended that you read! Ha. Totally my fault (I’m getting old). In any case, did you read through the article and the comments? If so, how did you conclude that in your scenario 2 the Tecton and frame binding would release, while the pin binding would not? By the way, I resisted changing from frame to pin bindings for some time, frequently arguing the virtues of frame bindings on this site. I have not seen the light. I am ski with Vipecs, and like the new Salomon pin bindings with independent brakes.

  311. Lou Dawson 2 September 15th, 2017 7:54 am

    Hi Russel, when I recommend skiing an “alpine” binding at resort, that includes frame bindings that are the same thing, only mounted on a frame. Now that the hybrid tech bindings are coming on, I might include those in that recommendation.

    That’s just my recommendation, it doesn’t mean I’m dead set against classic tech bindings at resort, nor that I think they are particularly unsafe. For example, a simple reason tech bindings are not so hot at resort is they’re more sensitive to icing and snow buildup, and folk tend to be in a hurry when they ski in a pack, jumping into bindings after lunch, chasing their friends down the hill, no time to “dyna-fiddle” for 5 minutes at the ski racks while you’re friends lap you.

    With all this a few factors intrude on thought experiments. Firstly, lots people, tens of thousands, ski tech bindings at resorts and I’ve not seen or heard of any huge increase in injuries. That could be due to all sorts of things, all the way from perhaps the bindings are better at releasing then one would think, or perhaps the type of people who use them are better skiers, or ski less aggressively, or whatever.

    Bottom line is it’s impossible at this time to determine if a properly adjusted tech binding vs an alpine binding is _significantly_ different in terms of protecting your legs from “ski” injury.

    That’s why I recommend doing the same process in decision making as one does in many endeavors. That of looking at your final goal and working backwards to your credit card.

    Thus, rather than doing all this conjecturing and thought experiments, and trying to pin me down with questions impossible to answer, how about you just tell us what you want to do with your bindings, and we discuss it from that angle?

    Real life vs theory.


  312. David Dodge September 15th, 2017 7:57 am

    Russel – in your scenario 1 the pin toes will release very easily once the heel releases in a forward fall unless you have the toes locked out in walk mode. The Vipec and Tecton need the bumper to release the toe in a forward fall because they are always essentially in walk mode unless there is a twisting load. A potential problem with these bindings is that during climbing they won’t easily release during an avalanche.

  313. Russell McGinnis September 15th, 2017 11:28 am

    Thanks for the Responses Guys,

    Lou- As you requested … I am looking for the binding to serve as a one-ski-quiver. Basically I want to be as light as possible, which is why I’m thinking tech. I need to be comfortable in the backcountry for the occasional ski mountaineering trip into tight chutes and also safe at the resort from pre-releasing and the occasional fall. I plan to do alot of touring this season like 50/50 alpine and backcountry and would like to use one set of skis.

    I enjoy these conversations and appreciate this amazing testing you guys did on tech bindings.

    David- How will the pin toes release in a forward fall (obviously unlocked) without applying some sort of twisting motion to those pins in a tech binding like the G3? Also could you describe how the Tecton would be less likely to release in an avalanche?


  314. See September 15th, 2017 7:26 pm

    Discussing bindings can be fun, but there is no such thing as one setup that’s optimal for all applications. Unless you’re traveling light, on a very limited budget, or have some other good reason to limit yourself to one set of skis/boots/bindings for a variety of applications, it makes more sense to get alpine skis for resort use and touring skis for touring, in my opinion. You don’t have to go off the deep end (like I have) and get powder skis, spring skis, freeride skis, and so on. And I respect my buddies who have been on the same set of teles for as long as I can remember (hey, they’ve kept up with the trends… those boards are now rockered even though they started out cambered). But if you’re into the nuances of how different gear performs, the one ski quiver is too limiting (again, imo). And it’s possible to get some pretty light alpine gear.

  315. Dave Dodge September 15th, 2017 8:03 pm

    Russel. Almost all of the twist resistance on most pin bindings comes from the heel unit. Once the heel is free the twist resistance offered by the toe is minimal as well as resistance to upward prying in forward fall. With the Vipec and Tecton the heel does not move to release in twist. The boot pivots about heel and slides at the toe. Once the deflection at the toe is sufficient the pins flop out the way and the boot is released. With these bindings it is unclear how they function in twist without a heel unit to pivot about.

  316. See September 15th, 2017 10:14 pm

    You lost me with that last sentence. Didn’t you just say in the preceding sentence that “The boot pivots about heel?”

  317. See September 15th, 2017 10:22 pm

    Unless you are wondering how the binding performs after a vertical release at the heel but before the boot has swung forward into the toe lever, releasing the toe. I also wonder about this.

  318. Russell McGinnis September 17th, 2017 7:32 am

    Dave – It functions similarly to a regular Alpine bindings by having the lateral release at the toe. Alpine bindings also need to overcome that wing deflection to release. Vipec and Tectons also have an added safety feature of releasing when the boot comes forward and hits the toe mechanism. It seems like this will be a very effective binding.

    Lou – This is pretty obvious to me that having an Alpine and Touring set-up is ideal but what would you go with if you wanted that one-ski-quiver?

    The Dynafit Radical 2.0s seem like a very fancy/reliable binding.

  319. Lou Dawson 2 September 17th, 2017 8:51 am

    Russell, there is no one ski/binding/boot combo that will do everything. If I was forced to choose, I’d first look at what kind of skiing I’d be doing, where in the world, etc. then pick my “quiver of one.” Instead of trying to pin me down with vague, open ended questions, how about you start with your end goals here, and we’ll work backwards from that? I’m guessing you’re looking for the quiver of one? In that case, share vital stats about the skiing you’re planning on doing, percentage human powered vs carbon powered, age, weight, years skiing, style, skill level, and some ideas on gear you’re already looking at, and perhaps a few folks here can chime in. Lou

  320. Pete November 28th, 2017 12:38 am

    Lou I will take you up on that if I may. I certainly appreciate all the analysis people have offered and I realize there is no simple answer or one size that fits all. I started skiing when I was about six and I’m 62. Until last year, that was all more or less inbounds resorts. Last winter I really enjoyed side country skiing. I made
    about half a dozen trips. I rented from two different shops. One had Marker Duke frame bindings the other Marker kingpin. I didn’t think much about the release/retention characteristics of the various bindings. I was a newbie, I took it on faith they would work well. I am not an overly aggressive or technically accomplished skier despite all my years on the mountain. I don’t have the confidence to ski everything and anything. I stayed on low angle slopes with minimal avalanche danger. Mine were all day trips. Typical climb involved 500 to 800 feet. I really enjoyed it and want to go back this winter in my own gear. I have an alpine set up that is about nine years old. I had a few falls last year but nothing that seemed too serious at the time. I realize however that a seemingly trivial mechanism can result in serious injury. I mountain bike all year long one way or the other and it was my go to for fitness. Blowing a knee or fracturing my leg would wreck havoc with my biking let alone working as I’m a good ways off from retirement and am on my feet constantly. One of my telemarking buddies blew out his Achilles and was scooting around for about six months at work. I’m content to keep it mellow, ideally getting out 10 or 12 times a winter for a day of earning some powder turns as a way to stay fit and enjoy the outside. Then again, I enjoy cruising the groomers on my alpine skis too. While it’s not a king’s ransom, getting a new set up with skis, bindings and boots is probably a $2000+ proposition. As much as I would like to get new alpine equipment and and an AT set up, that’s not realistic for me. I’m content to keep skiing my current alpine antiques on the groomers and committing to an AT set up to follow my new passion which has rejuvenated my love of skiing. Suggestions on boot type/binding/ski combo would be appreciated. There seem to be a lot of variations on the possible combinations and advantages thereof. In any case, thanks and happy trails.

  321. Lou Dawson 2 November 28th, 2017 7:46 am

    Hi Pete, what I always ask guys like you is could you spend the same on a ski touring setup as you do on a mountain bike? And if so, what’s the budget? Or if not, why not? Lou

  322. Pete November 28th, 2017 8:45 am

    Thanks Lou, yes I would readily commit to spending $2k+ or whatever it took to get the “right” set up. With so many options and various schools of thought, it’s hard for a newbie like myself to get some clarity. It is precisely because of the significant financial commitment involved that I hope to “do it right the first time”. I realize there is no “one-size-fits-all“ particularly for backcountry skiing. Thanks again.

  323. Lou Dawson 2 November 28th, 2017 9:14 am

    Ok, understood. In your case, I’d get a ski that’s pretty similar to what you’ve been enjoying, whatever that might be. For boots, just acquire one of the more downhill oriented touring boots, whatever fits. Examples would be Scarpa Maestrale or La Sportiva Synchro. Bindings are tricky. Despite the way they look and despite various marketing claims, there is no consensus nor scientific proof of what’s “safer.” If you’re an early adopter, the Fritschi Tecton looks good. Classic type tech bindings such as G3 ION are well proven though they most certainly do not have the safety retention/release of an alpine binding. You could try a frame binding such as Duke, but in doing so you need to be careful what boot you use, as frame bindings depend on the shape of the boot sole as well as lack of friction between sole and binding. Do you have a good ski shop you can work with on this stuff? Lou

  324. Pete November 28th, 2017 10:54 am

    Yes there is a healthy ski culture here. I’ll go pick some local brains but appreciate your insight and that of your contributors. One other question I don’t know if you have an answer for: I understand Rick Howell’s bindings are due to come to market in 2018. Am I correct in assuming those are only for Alpine skiing?

  325. Steven December 9th, 2017 8:19 am

    And so the Salomon S/LAB SHIFT MNC arrives as the comprise many might want between the Tecton (pins/weight/release properties at a lower weight) and frame bindings (elasticty, alpine release, power, feel at a higher weight).

    This style of binding would seem VERY desirable to the casual tourer who’s scared of the injury potential from traditional tech options (including the Tecton). I guess we’ll see next fall!

  326. Enjin January 29th, 2018 7:41 pm

    Here’s a video where I think Dave Dodge talks about the concepts in his first post above simplistically.

  327. John July 25th, 2018 7:29 am

    1) I notice a few new touring binding reviews on Blistergear, but release characteristics are sketchy. Is there still no touring binding with lateral release at the toe and forward/upward release at the heel to protect the tibia, and lateral release at the heel to protect the ACL ? The latter really IS the holy grail for touring bindings. The Salomon s/lab, which seems to be just an AT boot sole tolerant alpine binding with plenty of elasticity and tech climbing pins thrown in, is a long way off holy grail status IMHO. Even though it is the first non-frame binding that replicates the limited alpine standard (technology developed 60 years ago), it’s significant capability is still only tibia break risk reduction as offered by every bog standard alpine binding on the market.
    For those who can’t afford the their life to collapse due to a blown knee; an available feature never mentioned, but offered by all but 2 alpine bindings, and almost guarranteed to come with routine use of all touring bindings; ACL protective technology really is the holy grail.
    The engineering task required is well understood and well within reach.
    Companies have decided that Production of such bindings isn’t worth the cost, so maybe we need legislation to force development and reduce the load that these injuries put on the public purse. We have it with seat belts and crash helmets. Why should skiing equipment be any different ? Each year, an estimated 17,500 skiers tear an anterior cruciate ligament (ACL), accounting for about a third of all skiing injuries (University of Vermont School of Medicine).

    2)Has anyone considered investing a couple of hours to create an ongoing summary table of state of the art current bindings and new (tele and AT) bindings, with types of release, options (DIN or spring swap), prerelease characteristics, performance, degree of elasticity, compatible boots (providers and fittings required) etc. It would be hugely useful, and save thousands of skiers from weeks of PC research every year just to find out that nothing has really changed much despite the hype.
    Rock and run did a useful chart to aid rock shoe sizing.

  328. John July 27th, 2018 3:22 am

    Re Salomon S/Lab Shift:

    Could this really be the holy grail (ACL and Tibia protection ?

    This is what I got back from an Evo enquiry…

    “The heel and toes release both vertically as well as laterally. The binding cannot be skied in tour mode and the DIN range is from 5-13 for downhill.”
    Scott from evo

  329. Lou Dawson 2 July 27th, 2018 9:13 am

    John, I wouldn’t depend on retailers for binding technical reviews. Evo is good folks, but that’s not their job. Also, let me apologize for not more coverage of the binding, we got our signals crossed with Salomon and didn’t get quickly moving our usual process of bench and field reviews. Correcting that as we speak.

    Look for more soon here at WildSnow. In the meantime, NO, the Shift is just a regular “standard” alpine binding in downhill mode, nothing more.

    It is indeed rather hilarious (or sad) that we have just about every variation in helmets one could imagine, to help with a tiny number of head injuries compared to thousands and thousands of blown knees, that cost a fortune as well as often crippling people for life. As I always say, re helmets, buy three, one for your head and one for each knee.


  330. John July 27th, 2018 9:46 am

    Bother. Thanks for clarifying about the shift.
    Is there still really no touring binding with lateral and upward release at toe and heel, or even 3 of those 4 options ?

  331. john July 27th, 2018 9:48 am

    …that is, other than the Voile CRB releasable on 20mm riser.

  332. Lou Dawson 2 July 27th, 2018 11:24 am

    John, not really. Classic tech bindings release to the side at the heel as well as having a modicum of toe lateral release, but the toe release is “blocked” at a certain point, thus making it fairly meaningless in terms of contributing to leg protection. As I harp on here occasionally, skiing with a minimal amount of falling, and learning how to fall safely, those things can make a huge difference. No ski binding can totally protect, people blow their knees hiking. Lou

  333. John July 27th, 2018 11:29 am

    Yes, it’s in the forests (most of my backcountry) with frequent submerged deadfall and stormfall that has me looking for upward at toe really.

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