Evaluation of Tech Binding Release Function

Post by WildSnow.com blogger | March 21, 2016      

I spend a lot of time trying to explain this in writing. Sometimes a video is better. Here you go. See below for clarifications in writing.

Important points:
1. This video illustrates checks you can do on a “classic” tech binding, meaning it has pins that insert in boot at toe and heel, releases to the side at the heel, and does NOT have a rotating toe. Nonetheless, these concepts can apply to bindings with rotating toe, and the lever release check works on nearly any binding, though you should only use the lever check on vertical release settings around 6 or lower, to prevent damage to ski, binding, or boot. I miss-stated this in the video.

2. The CONCEPT of these checks does apply to bindings such as Radical 2.0 with rotating toe and Kingpin with different type of upward release, but what you see during such checks on such bindings will be different than what I illustrate in this video. MORE, with bindings such as Kingpin you may need to test lateral release function with binding set to your normal release settings as the Kingpin lateral release spring needs to apply force to the boot to overcome friction at the brake AFD under the boot heel. Note that classic tech binding lateral release function can also be tested at your normal settings, it is the vertical release function test using a lever that requires lower settings, to prevent use of excessive force.

3. These evaluations are not used for setting release values, they are simply ways to evaluate if the binding actually releases and has correct return-to-center function as well as a modicum of elasticity.

4. These tests should be done at moderate release value settings so as not to place undue force on binding components. Settings around 6 or lower seem to work well. More, be sure the correct heel gap is set for your test bindings per manufacturer specifications.

5. IMPORTANT: If you observe any problems with these functions, cause can be either the boot or the binding, or sometimes a combination of both. Evaluate using A-B testing with different boot binding combinations. For example, a guy came by here the other day with a setup that seemed to be “grabby” in side release as well as prone to pre-release. Turned out the binding toe pins were excessively worn, his boot worked fine in a newer set of bindings.

6. If any of these tests appear to require excessive force, re-evaluate before you proceed as you could damage your ski, boot, or binding.

7. By watching this video and visiting WildSnow.com you agree that you perform all such testing and evaluation at your own risk.

8. Some bindings in my experience seem to not be designed to give the smooth lateral release function as shown here, ditto for boots. If you have such a binding you’ll need to decide if having smooth release and elasticity are worth it to you, or not. Your choice.

9. Rotating toe of Radical 2.0 and Beast, and side release toe of Vipec and Trab all eliminate problems with the toe “ball and socket” joint catching or otherwise not moving freely.

Comments appreciated.


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27 Responses to “Evaluation of Tech Binding Release Function”

  1. Zorba March 21st, 2016 11:21 am

    Interesting video, thanks. Nice and clear.

    Two things I noticed:

    1. in the detail of the toe action during lateral heel release, it looks like the left pin releases (completely out of the toe piece) before the heel has completely released. If you had let the heel return to centre at that point instead of continueing, what would happen? Would both heel and toe reset or would the heel be unable to return without the toe pin aligned?

    2. (This is definitely betraying my lack of experience) what happens at the toe after a heel-only vertical release? Presumably the toe usually releases moments later as the crash continues and horizontal rotation forces apply?

  2. Lou Dawson 2 March 21st, 2016 11:26 am

    Hi Zorba,
    1. There is indeed a point where if the stars are aligned the heel can return to center even after one of the pins has come all the way out, problem is that the toe is just about to fully release by then as well, generally you’d come out in real life at that point.

    2. After the heel-only vert release I’ve demonstrated, the boot yes indeed comes out of the toe one way or another, and the force required to do so is very low, sometimes around RV 3 depending on angle of boot and brand of binding.


  3. Zorba March 21st, 2016 12:03 pm

    Thanks 🙂

  4. John Mattson March 21st, 2016 5:06 pm

    I’ve been using dynafits for a long time, and I’ve had quite a few instances where the heal released, and the toe didn’t. I consider this to be very beneficial, because you save your leg, and don’t loose your ski. I will often put the tow in bare trap mode on extreme slopes, where loosing a ski could be extremely dangerous

  5. Seth March 21st, 2016 8:20 pm

    Thanks for the excellent video. I tried this tonight with my setup

    DPS wailer 99
    Kingpin 13
    Tlt 6 “black”

    Lowered din to minimum and torqued the heel but the heel piece does not want to re-center itself when torque is removed. Heel returns about 1/3 of total angular displacement. Cannot get full lateral release!

    Same results with Atomic Backland carbon boots with the forward pressure adjusted for BSL change.

    Not confidence inspiring.

  6. See March 21st, 2016 8:45 pm

    Nice and helpful video. Reminded me how much I wish I could get some sliding AFD’s for my Verticals. The binding action in the video is much smoother than I get with the rubber boot sole sliding against a fixed plastic brake pedal. I’m pretty sure they’re not “catching” due to some pin/socket problem. (Seth, I have no experience with Kingpins, but they look like they clamp down on the boot heel with a fair amount of pressure. Do they release smoothly if you just push the boot heel to the side?)

  7. Lou Dawson 2 March 22nd, 2016 6:01 am

    Hi Seth, the test I demonstrate in the video is for classic tech bindings, defined as those that have pins inserted in boot fittings at both toe and heel, with a rotating heel unit. Kingpin as See says has a lot of downward pressure on the boot heel that can induce some funny behavior, firstly you should test lateral return to center with binding set to you normal release values as the lower the release value the less return to center force the lateral release spring will exert. I’ve also found that shaving a millimeter or 2 of some boot soles used with Kingpin, just over the AFD, helps reduce the sometimes extreme downward pressure. Also know that this is a test, it is not real life. There is never a test that can 100% match real life ski conditions. For example, perhaps the vibration and pressures while actually skiing can overcome the friction or whatever it is that’s preventing your Kingpin return to center.

    Again, with Kingpin, test lateral release return to center at normal release values. Reduce somewhat for testing vertical release just to prevent use of too much force.

    When testing lateral release function of classic tech binding, it doesn’t really matter what number you have the lateral release set on. I just suggest lowering it so it’s easier to do the test. But again, do lower the vertical setting to prevent use of excessive force.


  8. See March 22nd, 2016 7:28 am

    Re. Verticals: I also checked for sole lug interference with the brake pedal. Resistance to lateral movement is more or less constant (not hanging up on a lug). Putting a thin plastic bag between boot and brake noticeably reduces friction and improves return to center.

  9. Mike McT March 22nd, 2016 12:58 pm

    Hi. A bit off topic, but needed help from the Wildsnow community.
    I have Radical 1.0 bindings. The AFD on my right brake popped off. I found the plastic plate in the skin track. But there must be some type of spring that pulls the plate to the on-center position. I was unable to find it.
    I’ve filled out the customer service request on the Dynafit website 3 times. Then I enlisted the help of my local ski shop. They’ve been entirely unresponsive. Which is weird as this will theoretically change the release properties of the binding.

    Can anyone suggest a way to get a remedy for this? Really shocked that Dynafit would have such a “nobody home” approach to customer service…

  10. Lou Dawson 2 March 22nd, 2016 1:36 pm

    Mike, your best bet in my opinion is to just remove the brake from the binding and use a leash when necessary. Lou

  11. GeorgeT March 22nd, 2016 6:05 pm

    I think the “Carpet Test” would be a great follow up video. I was impressed with your tests on a 9 year old boy and what I learned in the process.

  12. Lou Dawson 2 March 22nd, 2016 7:00 pm

    Hi George, good suggestion, I’ve been thinking of that… a little tougher to present as there is a safety aspect. In the industry I hear people calling it a “self test” but I like carpet test better, as it should be done on carpet or a friction mat. We shall see. Lou

  13. See March 22nd, 2016 8:08 pm

    Leashes have advantages, I guess, but it would be nice if the AFD’s didn’t self destruct.

  14. Paul March 22nd, 2016 9:20 pm

    I tried this with my new Dynafit Superlight 2.0 set up. I was curious because they require a lot more force to get into than my Vertical ST set up (set to about 8). I can’t see a practical way to simulate an upward heel release short of a mechanism that pulls from above as the binding sits too low to get any kind of effective prying tool underneath the heel. I’m concerned about the much higher force required to get in – it seems like the force to get out should be much greater as well. I wonder now what the effective upward release is and if I have a really light pair of non-upward releasing bindings now?

  15. Lou Dawson 2 March 22nd, 2016 10:34 pm

    Hi Paul, according to some folks the vertical release value of the Superlight 2.0 springs they shipped to North America is somewhere around 12, which is possibly why they are so hard to stomp down into. You can get a prybar under the boot instep, can’t you? But that would require a huge amount of force and probably not a good ideal. My method isn’t going to work for everything… Lou

  16. See March 23rd, 2016 9:07 am

    Hi Lou. Maybe you could put that instrument from the toe spring rig to use measuring heels. The numbers would likely be interesting in a relative sense– comparing non adjustable heels with adjustable ones at known settings, comparing one bindings retention at a given rv with another at the same setting, etc.. Some sort of stirrup placed at a set distance from the rear pin fitting pulling straight up?

  17. Lou Dawson 2 March 23rd, 2016 9:15 am

    See, I figured out how to measure, using a lever arm that’s an exact distance from center of pivot, it’s just a matter of time to implement. If the lever arm is a meter long than I can just measure the newtons, result is newton-meter of torque, Nm or so I’ve been led to believe by my engineering mentors. A meter might be a bit long, I’ll probably do it with 1/2 meter long lever, or even 1/4, then do the math.

    The BIG problem with this is just measuring the heel would not translate between brands and models, since the resistance of the toe springs also comes into play. Ultimately, you have to test a boot in the binding, and in that case the numbers get whacked all over the place and the results are next to useless other than to show how primitive all this really is. Skialper magazine already did it, no need to reinvent the wheel.


  18. Paul March 23rd, 2016 3:20 pm

    Hmm, I was thinking based on rumors that the fixed upward release value was equivalent to a 9 or so, higher than I’d like but tolerable. For me, 12 = non-releasable and non-starter. I went over the tips with these this morning for the first time and came away limping (no release). I know the wise thing to do is set these aside for now and get the less stiff springs in the fall, assuming they appear, but the generally unwise and dominant side of me is looking at taking the springs out and doing some grinding. Have you tried removing those U springs? It looks like simply driving out the pin that the heel riser pivots on will allow them to be tapped out, but I’d be more comfortable hearing from someone who has already taken that U spring off.

  19. Lou Dawson 2 March 23rd, 2016 3:55 pm

    Hi Paul, Bill Bollinger says you can reduce release force by grinding the arc area of the spring. I did not do so as I was afraid of weakening it and having them break in the middle of nowhere, as well as having no good way of testing the release.

    Any reason why you can’t just get some springs from Sport Conrad? Seems like that would be super easy, as shipping cost would be minimal.


  20. Bar Barrique March 23rd, 2016 8:07 pm

    Well, I looked at the Superlights, and, bought ATK. This Dynafit binding is hardly a revelation with a fixed vertical release, and, no flat walk. The removable brake is IMO, the definition of a “gimmick”.
    The real issue is that Dynafit has “on the shelf” options to produce a very nice light binding, but has elected to produce a “novelty” one instead.
    This may be what happens when the Marketing Department is running a Company.

  21. Paul March 24th, 2016 3:15 pm

    I got access to a Vermont Ski Safety Release Calibrator at SkiMo.com and tested my Superlight 2.0 upward release tension. For a baseline, I measured my Vertical ST bindings set to 8 – the measured release value was 8.5. The Superlight 2.0 unmodified had a measured release value of 11. Reducing the spring diameter from 4.9 to 3.7 mm dia, grinding just the outermost portion of the spring across the curved portion that I could access without removing the spring, reduced the measured release value to just under 8, right where I wanted it. I was careful to grind only longitudinally as smoothly as I could by hand to avoid creating any stress risers. I’m not too concerned about the spring breaking but will report back if I guessed wrong. The guys at SkiMo told me they have done a similar mod several times before with good results. Problem solved (I think).

  22. Paul March 24th, 2016 3:17 pm

    Forgot to mention – I can’t find any Dynafit parts on the Sport Conrad site, although they do list the W’s version of the Superlight.

  23. Lou Dawson 2 March 24th, 2016 3:31 pm

    Hey Paul, excellent info! Release value 11, wow!

    Still sounds like a risky mod to me, but if SkiMo is getting good results then so be it. I hope they have a good liability release form for customers they do these types of mods for!


  24. Paul March 27th, 2016 9:32 am

    Doesn’t seem too risky to me, but I am familiar with stress distribution and metal fabrication and have access to quantifiable testing equipment, so perhaps am in a unique position. In terms of liability, I guess it is debatable on who is exposed to more, a shop modifying a binding or a company selling a touring binding with a release mechanism that is essentially non-functional for most customers. And interesting that a discussion of a really interesting new binding immediately shifts to liability concerns. Only in the USA….

  25. Lou Dawson 2 March 27th, 2016 10:55 am

    Paul, I’d agree that so long as a lot of material is not removed, and it’s done with care, it’s perhaps acceptable. On the other hand, unless a person has a way of measuring release value, I don’t see how this mod is workable other than in an imaginary sense…and I maintain that it could weaken the spring to the point where it breaks in use. I’d also agree that it’s pretty surprising Dynafit NA would distribute a binding with virtually no upward/forward release for all but very large skiers, while it appears to have release on visual inspection of machinery. I’ll bet they just never imagined this would be the case. It would have been so easy to provide the normal strength springs…

    As for liability, the EU is no stranger to this stuff. They’re ones arresting people for starting avalanches, for example. And the CE standards are quite a bit stricter in some cases than ours are, causing all sorts of extra and sometimes unnecessary work for product designers.

    As for ski shop liability, I’m always delighted to see modding going on. But I can’t help but think there are some serious legal risks involved in modifying safety equipment such as ski bindings, for a customer, (assuming) without the kind of equipment and metallurgy that could be used to defend against an accusation of negligence. Far be it for me to tell anyone how to run their business (grin), I just couldn’t help but mention it. Stimulating discussion and all.


  26. Nelson January 14th, 2017 7:05 pm


    I assume in this test the binding is set to ski mode. However, I understand that due to pre-release concerns many will descend in tour (locked) mode. Would be very interesting to see what happens in that (real world) situation in comparison. Or would it just mean you wouldn’t be able to get a lateral release (without much larger lever)?

  27. Lou Dawson 2 January 14th, 2017 7:19 pm

    Nelson, yes of course, binding set to downhill ski mode. If this test was performed with toe locked in uphill tour mode, yes, there would be no practical side (lateral) release to test, doing so would be pointless. Lou

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