How Elastic is the Plastic? Tech Binding Research


Post by WildSnow.com blogger | June 17, 2016      
Vipec lateral travel test rig.

Vipec lateral travel test rig. I did not go to extremes with this, as it’s tough to measure to the exact moment of release. Thus, all measurements are for the sake of comparison and while accurate within a few millimeters are not intended as specifications.

A bit of bench work regarding “elasticity” and “travel” of touring bindings, defined as how far your boot can move in the release function and return to ski mode without ejecting (i.e, “return to center”). Thus ostensibly “absorbing” shock and vibration.

First, let’s talk vertical heel elasticity. It bears repeating that the classic tech binding configuration has minimal vertical travel at the heel, about 4 millimeters (as compared to the alpine binding benchmark we go by: around 10 millimeters). For smooth skiers used to tech bindings this tends to be a non issue, but with stiffer boots and aggressive skiing, many (if not most) riders find they need to dial up their classic tech binding heel vertical release settings or otherwise experience the “insta telemark” heel pop-out effect — and subsequently a full and dangerous pre-release.

Vertical heel travel of a classic tech binding is dictated by how far the binding pins move down and out of the binding as your heel moves up, a minimal distance as indicated by the arrow.

Vertical heel travel of a classic tech binding is dictated by how far the binding pins move down and out of the binding as your heel moves up, a minimal distance of about 4 millimeters as indicated by the arrow. Soft touring boots and smooth skiing obviate this as a performance factor, but go fast in big boots and you might find your heel popping up and out of the binding unless you dial up your release value to stratospheric levels — essentially locking the binding.

As of 2016, three bindings with “tech” type toes (i.e., pins that insert in boot toe) exist that have extended heel vertical travel. (Classic tech bindings do have spring loaded pressure holding the toe wings closed on your boot in alpine mode, and the amount of that pressure is important, but we don’t count this as providing travel or elasticity that can be compared to alpine bindings, read more here.) As follows:

Trab vertical travel, measured just before the heel grabber goes over-center and releases boot heel.

Trab vertical travel, measured just before the heel grabber goes over-center and releases boot heel.

Trab TR2 uses an elegant over-center pivot resisted by a beefy coil spring; yielding about 10 mm of travel. Downside is you have to actively hold the binding open with your ski pole to enter alpine mode.

Dynafit Beast has at least 11 millimeters of vertical heel travel, impressive and actually more than some alpine bindings, but with a twist. Beast vertical heel release occurs in two stages. First, a large coil spring absorbs energy and allows travel of about 8 mmm with adjustable tension, then a set of classic tech style heel pins take over release function and ride down and out of the heel fitting just as with any other classic tech binding. Interestingly, the heel pins do not have adjustable release tension, and appear to be set at a release value of at least 10. Result is when set at higher values, Beast vertical release behaves normally, but when set to lower values you get a vertical release value “spike” when you engage the heel pins during the final part of the release. We thus only recommend Beast for skiers using fairly high release values.

Dynafit Beast heel with '1st stage spring' indicated by arrow.

Dynafit Beast heel with ‘1st stage spring’ indicated by arrow.

Marker Kingpin boasts a heel unit that behaves similar to a full-on alpine heel in vertical release and travel. Its ~9 millimeters of vertical travel is not as much as shelf appearance would indicate, but is virtually the same as our alpine binding benchmarks. Thus, excellent.

Boot with regular DIN-ISO sole shape fits in Kingpin with no adapter.

Marker Kingpin heel at first glance is a normal alpine unit, twist is it “twists” to the side to effect lateral release at the heel, similar to all classic tech bindings.

Our alpine binding benchmark for this evaluation.

Our Salomon alpine binding benchmark for this evaluation has about 10 millimeters of vertical heel travel, a common range for alpine grabbers.

Heel vertical elasticity (range of travel before release):
Dynafit Beast ~ 11 mm (two-stage vertical heel release, first stage adjustable but second stage fixed)
Alpine (Salomon) binding: ~10 mm
Trab TR2: ~10 mm
Classic tech binding and Vipec: ~4 mm

Toe lateral elasticity (only measured for “toe release bindings”
Alpine (Salomon) ~20 mm
Fritschi Vipec ~17 mm
Trab TR2 ~10 mm

Heel lateral elasticity (classic style tech binding and Dynafit Beast)
My instincts tell me it’s difficult to correlate/equate lateral heel travel with toe travel. So let us not go there. Suffice it to say that nearly any classic tech binding (side release at heel) has about 12 mm of travel when the heel unit rotates to the side. Tech bindings with rotating toes (i.e., Radical 2.0, have slightly more functional range due to the toe pins staying fully engaged with the toe sockets for the full range of motion, while classic binding pins ride out of the boot toe sockets and may become sensitive to pre-release when not fully engaged (that’s the party line, anyhow, while in my opinion such doesn’t matter unless you’re skiing aggressively, proven in real life by hundreds of thousands of skiers on classic tech bindings.)

In any case, only two tech bindings exist with lateral elasticity at the toe, as follows.

Fritschi Vipec Black toe.

Fritschi Vipec Black toe. The toe pin ‘wings’ move to the side on a sliding carriage to provide travel and release.

Fritschi Diamir Vipec in its latest incarnation (Black, 12) has an impressive ~17 mm of travel due to a sliding carriage with lots of room to move. Other versions have 30% less travel that’s entirely adequate for most skiers. See this post for details.

Trab has a simple and downright elegant system of spring loaded cams that go over-center to release the toe wings.

Trab has a simple and downright elegant system of spring loaded cams that go over-center to release the toe wings.

Trab TR 2 uses an interesting and quite elegant system of small spring-loaded pivots that engage with the toe wings. This system measured as about 10 millimeters of travel in my tests, around half what an alpine binding gives you but again in my opinion quite adequate for most skiers. As with Vipec, you have to reset the toe wings by hand after a lateral release.

In view of lateral elasticity, it’s worth mentioning Marker Kingpin as the appearance of the heel indicates it perhaps has superior lateral travel. Kingpin heel does have good lateral elasticity and return-to-center if adjusted properly and used with compatible boots (mandatory bench testing), nevertheless it has no more lateral travel than any other classic tech binding due to the finite limit created by the boot toe sockets riding on the binding toe pins.

What about “heel power?” You’ll hear marketing spreech about more “power” and a “solid feel” of the heel you get with Kingpin, Vipec and Trab due to various factors. On the bench, those bindings clearly clamp your boot with less rolling (cuff side-to-side) play than “normal” tech bindings. You can feel this when you ski various test rigs using the same boots. Do you ski better as a result, or have more fun? Your call.

In summary, while the vertical heel elasticity/travel of our test bindings easily matched that of many alpine bindings, lateral travel at the toe was somewhat less and varied quite a bit between brands. All these bindings in their most current iterations have field tested as mature products with no known defects. While we’re not sure if any of these bindings offer more protection from leg injury than classic tech bindings, they clearly have more elasticity/travel and thus could be better choices for aggressive skiers.

Decent quality alpine bindings have quite a bit of lateral travel at the toe,  often assisted by a 'forward pressure' preload that helps the boot return to center when displaced.

Decent quality alpine bindings have quite a bit of lateral travel at the toe, often assisted by a ‘forward pressure’ preload that helps the boot return to center when displaced. Forward pressure preload doesn’t help tech bindings and none have it, neither the “classic” tech bindings nor the new breed of hybrids. This is an important point, it may very well be that it’s impossible to build a lightweight toe-release tech binding with the return-to-center force of a modern alpine binding. Keep that in mind when you adopt tech bindings as your ‘quiver of one’ for all your skiing.



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Comments

21 Responses to “How Elastic is the Plastic? Tech Binding Research”

  1. Bar Barrique June 17th, 2016 10:06 pm

    Good stuff, though I have been happy with traditional tech bindings, your research seems to indicate that an AT binding of reasonable weight could offer “state of the art” release specs.
    So it seems that the question that begs an answer is ; could the Vipec toe piece be compatible with the Kingpin heel piece?

  2. Powbanger June 18th, 2016 7:44 am

    Howdy Lou
    I would think forward pressure helps all all bindings from pre-releasing. Why do you feel it is not needed in tech bindings?
    Published vertical realeases in alpine bindings run from 12mm-27mm, Lateral from 13mm to 45mm. It’s interesting you’re seeing less than those numbers in bench testing, though certainly not surprising.
    This is great info Lou.

  3. Lou Dawson 2 June 18th, 2016 8:07 am

    This stuff gets technical. An important point I made in the article is that none of the classic or hybrid tech bindings have any sort of forward or backward pressure that helps the binding return to center after side (lateral) displacement. Adding to that, the classic tech system is nearly friction free when used without a brake, or if the brake has a functioning AFD. Alpine bindings in my opinion use friction as an actual energy absorption/damping device. Of course, friction is also the enemy of consistent safety release and good return-to-center action. It’s thus a tough balance and one that can change with the introduction of dirt on binding surfaces, boot wear, and in the case of tech bindings, fittings that are out of spec or worn. Indeed, I’m seeing more and more worn out tech binding toe pins and boot fittings now that so much pintech gear has been around for so long. These worn components are revealed in bench release checks. Lou

  4. Lou Dawson 2 June 18th, 2016 8:18 am

    Powbanger, I’ve got two representative alpine bindings here and both measure about a centimeter in vertical heel travel. I’ve looked at others as well and they appear to be in that range. Perhaps they’re actually a few mm better than that when perfectly measured, thus being 12 mm. As stated, I couldn’t measure perfectly but did so to the degree where I think I can validly compare everything.

    As for lateral travel, the Salomon alpine binding I have here is good quality though several years old. It has both toe height adjustment as well as toe wing angle adjust. I measured the travel quite a few times and tried to be as generous as possible, but I also was pretty strict about only measuring to the point where I thought the boot could reliably return to center. I’d imagine the manufacturer specs are much more optimistic and measured with new, perfectly adjusted bindings with new boots. More, they might have a different way of measuring. I just measured how far the boot toe could go to the side and still return to normal position without releasing from the binding.

    Everyone, please get over the “forward pressure” thing. In most configurations of tech bindings, with the boot toe riding on the pins, it would have no benefit and probably even contribute to pre-release. You do get some forward pressure when the ski flexes and the binding has to compensate for curvature of the ski. Which is interesting, as the newer binding with zero heel gap and a ski flex compensation spring do add pressure to the equation, while the classic tech binding that allows the boot fitting to slide forward and back on the heel pins exerts much less pressure, at least until the heel gap closes up. Such can be demonstrated by simply flexing a ski with a boot in the binding. Anyone with a bent towards the details of tech bindings should do this now and then and observe.

    Lou

  5. Lou Dawson 2 June 18th, 2016 8:20 am

    Bar, clearly you have not been reading WildSnow enough (smile).

    https://www.wildsnow.com/19548/combine-vipec-kingpin-bindings/

    Using a Kingpin heel with Vipec toe would give you the vertical elasticity of the Kingpin, but it provides no lateral release at the heel due to how the Vipec toe functions. More elasticity is good, but most people I talk to about doing this sort of combo seem to be more interested in the safety that might be provided by having lateral release at both toe and heel.

    As I alluded to in the blog post linked above, I will not be surprised if Fritschi springs a new binding on us that uses the Vipec toe only with a heel that has plenty of vertical travel rather than the meager 4 mm it presently has. When that happens it will be impressive and could truly be a tech binding that’s an alpine binding.

    Lou

  6. Powbanger June 18th, 2016 10:07 am

    Salomon, Tyrolia, older Marker all have very similar heel pieces and thus vertical elasticity. Look and new Marker (Kingpin as well) have about twice as much vertical elasticity. Lateral elasticity is measured at point of release, so usable elasticity (your method) certainly makes more sense, to me anyway.
    Forward pressure comes into play with counter flex (rebound) more than flexing the ski. To me, it plays A large role in reducing the dreaded mystery tele, that sudden vertical release of the heel because counter flex allowed the pins to clear the heel of the boot. It’s also a contributing factor in using tech bindings at resorts as the snow is firmer and variable terrain can increase the counter forces.

  7. Lou Dawson 2 June 18th, 2016 10:23 am

    Indeed Powbanger, the “heel cup pivot” type of alpine heel unit, re Marker and Salomon and hundreds more, all are nearly the same thing and have very similar vertical travel/elasticity. Extended travel beyond about a centimeter sounds nice but clearly is not necessary for most skiers. Lou

  8. See June 18th, 2016 10:32 am

    Wildsnow binding tests are great. Thanks again Lou.

    I wish there were good data regarding how various bindings perform in actual use. Aside from anecdotal evidence/personal experience, such information is not available (as far as I know). The next best thing is probably observing what equipment knowledgeable people are using and (just as important) how they are using that equipment. Based on my very limited observations in the field and on the interwebs, I’d say classic tech still rules for human powered skiing (but many of the people I ski with are on teles, so what do I know?).

  9. Powbanger June 18th, 2016 1:11 pm

    Thanks Lou
    I’m not sure about hundreds more heel binding designs, but there are very real benefits of vertical elastic travel beyond 10mm (for every skier) sock absorption for beginners, extended travel before vertical release for expert level skiers.

    See – the data you are looking does exists. Most binding companies have real time test results they will share with retail shops if asked.

  10. See June 18th, 2016 6:31 pm

    Thanks Powbanger. I’ll look into that. The sort of information I’m interested in would be largely statistical, like number, type and cause of injuries per skier day for different model bindings. Accurately defining, determining and controlling for things like skier type, conditions, terrain, release values, what counts as a “pre-release,” etc. would be very challenging. If some manufacturer/ graduate student/ research institute has collected and analyzed data of this sort that could support claims like “tech binding X performs as well as most alpine bindings in terms of lateral release and retention” that would be very interesting.

  11. Floyd June 18th, 2016 7:50 pm

    Hey Lou,

    Slightly off topic here but how often does ski flex cause a pre-release of a properly set up and adjusted binding? Often enough to justify a something with a tensioned heel piece like an Ion LT over something like a Superlight?
    I poked around and found out that the burliest binding the Dorais brothers ski is a speed toe with a race heel for their mountaineering and ski touring objectives, and that piqued my interest in the Dynafit expedition binding. Not recommended for mortals?
    I’m a tele skier switching to AT for more mountaineering style objectives and couloir hunting. I currently rock Hammerheads and Axles so release is something I’ve never really thought about much.

  12. Powbanger June 19th, 2016 9:02 am

    See – Most or all of that info is around, as our litigious world compels binding companies to do extensive tests and evaluations when products are brought to market. Getting your hands on that detail of information will be very difficult. ASTM has a yearly conference you may want to lconsider attending. I’m sure you’ll find answers concerning your injury and DIN specfiic questions.
    I don’t think you’ll find much detailed info on tech bindings yet. They are just starting to fall under DIN norms which will require shops to do additional release tests to satisfy company indemnification requirements, just like alpine bindings.

  13. Lou Dawson 2 June 19th, 2016 11:14 am

    Floyd, ski flex cause pre-release in a number of ways. With tech bindings, if your ski flexes heavily it can cause the heel of your boot to bang into the binding and place too much pressure on the toe pin/socket, in the reverse, if the ski “reverse cambers” too much it’ll pull the heel pins out of the boot heel. I think there are other modes as well. Despite us liking to think our ski bindings are so high tech, they’re actually pretty primitive in my opinion. Vermont Ski Safety has a really good FAQ about inadvertent release: http://www.vermontskisafety.com/vsrfaq5.php

    They talk about about many many ways accidental release can happen, and cover the “Ratchet Effect” meaning the tendency to just dial up release value settings thinking that doing so will cure all modes of accidental release, which doing so clearly does not accomplish though it can help when all else fails, depending on what’s really causing the releases.

    Lou

  14. Pablo June 20th, 2016 5:20 am

    Talking about the “insta telemark” heel pop-out effect, vertical heel elasticity is no so important on clasical tech binding as in alpine bindings is.

    In my view, when your heel pops-out on a tech bindings… first, you got your toes already enganged, and second, when your heel stomps again against the binding the heel re-engages instantly so you have lot of chances to recover control.

    When you pop-out the heel on an alpine binding, well…. you just pop-out….
    First, your toe goes of… and also, most of times when an alpine heel pops-out the lever usually goes to “close” position so it’s imposible to re-engange the heel again. That will be the case of Kingpin.

    So, for an alpine binding is far more important the ability to return the boot heel to its place than for a tech clasic tech bindings.

  15. Lou Dawson 2 June 20th, 2016 7:32 am

    Everyone, I’ve been remiss in not pointing something out that we should all have imprinted on our DNA: Just as Vermont Safety points out, tech bindings are not immune to accidental release modes that can’t be mitigated by just ratcheting up your release values, and that may not be mitigated by basic “travel” and “elasticity” features as covered in this blog post. The problem of ski “reverse camber” flex pulling the pins out of the boot heel is one example, as is the binding not compensating for regular ski flex in a turn, thus causing the boot heel to “jam” against the binding heel unit, thus forcing the toe fittings off the binding toe pins.

    Might be time for some writing about ski flex compensation in tech bindings. Perhaps we should continue the work we started for the following blog post:

    https://www.wildsnow.com/6468/dynafit-ft-12-radical-binding-damper-stiff/

    Lou

  16. jw7 June 20th, 2016 8:35 am

    I don’t want elasticity, I want a binding that keeps my boot aligned correctly until I need to release and then I want to get out of the binding as quickly as possible.

  17. See June 21st, 2016 7:34 am

    Seems to me that fore/aft heel piece travel/elasticity should go a long way toward mitigating accidental release caused by the heel pins pulling out when the ski over-cambers or by the toe piece letting go when the ski is is heavily flexed and the heel piece jams the boot forward. I’d rather have a binding with this fore/aft “elasticity” than some sort of ski flex damper in the binding. Better just to make a damp ski, imo.

  18. Lou Dawson 2 June 21st, 2016 10:06 am

    See, I’d mostly agree, problem is it’s really hard to build in much fore/aft travel in an AT binding of any variety, and doing so with a tech binding seems to create a lot of forward pressure when the ski is flexed, which can work against preventing accidental release. Frankly, the old method of just having the boot heel fitting ride on the two steel pins is the Occam’s Razor solution. It’s brilliant and could perhaps even be improved by adding a few extra mm to the pins in length, and a few .01 mm diameter to the pins. Classic Tech 2.0 could do this and only require a swap of the boot heel fitting. They could make it a few mm wider while they were at it. I’ve asked Fritz about this and while he reminds me that all such changes have unforeseen consequences, he says it could be done. However, he also is where I got the POV that if, yes, hundreds of thousands of ski tourers seem to be doing ok on classic tech, why change? Lou

  19. Bob November 9th, 2016 7:18 am

    Is there a list of incompatible boots with the new Vipec binding? In a Fritchi produced video they show that the black La Sportiva Spectre boot has too much sole rocker and will not work. How about the new Dynafit TLT7 with it unique toe shape? I think a list of boots that will not work in this binding would be helpful.

  20. Lou Dawson 2 November 9th, 2016 8:39 am

    Bob, I agree, a list of incompatible boots would be helpful. But I don’t think it’s more than a handful, and an argument could be made that it’s the job of the retailers to help consumers sort this sort of thing out. More, the boot landscape changes rapidly. Perhaps Fritschi will publish some sort of list, but I wouldn’t hold my breath, more likely is they’ll continue to communicate about issues that need to be checked for. Lou

  21. nate porter November 9th, 2016 7:20 pm

    Lou, It could also be argued that if a binding maker wants to sell more bindings, it would behoove them to make it clear what boots will work with the binding. I agree that retailers can provide lots of useful compatibility information- they see lots of different combos of gear come through their shops. But probably only the shops that either sell or service enough volume of boots and bindings will see enough possible combos to know what works and what doesn’t. As you point out, the boot and binding landscape is changing quickly. Compatibility issues can be hard to keep up on. On the other hand it is knowing about things like compatibility that hopefully helps retailers keep customers. Disclosure- I’m a retailer. I’m also a longtime fan of your site. Thanks for providing a great resource to the backcountry skiing community.





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