Measuring Release Values — Salomon-Atomic U-spring bindings
‘Twist’ testing.
I’ve acquired a Vermont binding release checker. While this tool is designed for toe-wing (alpine) binding release checking of TUV certified DIN/ISO standard systems, it correlates well when used to evaluate lateral (twisting, side) release and retention of classic tech bindings. To verify, I checked a set of Dynafit Speed Radical I’ve got mounted up for my current Cosmos 3 boots, as well as testing with my quite used TLT-6 boots. Dynafit binding set on 8, checked out with release value (RV) of 7.5/8 on the torque wrench using my boot choices, other experiments showed good results as well. Thus knowing the Vermont instrument would give me usable results (at least for comparisons), I then played around with the Salomon-Atomic U-spring bindings.
Lateral, twisting, results (informal averages of several test cycles):
7 with the “Women” spring using Cosmos, and 6 with the TLT-6 (makes sense, see below for info about testing with no heel spring).
8 with the “Men” spring, Cosmos, 7 with TLT-6.
10 with the “Expert” spring using Cosmos, 9 with TLT-6.
(Vertical, forward release is challenging to measure accurately with the Vermont device due to the limited elasticity of tech bindings, but the numbers I got seemed fairly consistent with the TLT-6 lateral results. The “Expert” spring took so much force I was afraid of breaking the ski, so I didn’t get a measurement at that extreme, I’d imagine it’s at least 11.5. The “Men” spring measured 8.5 and the “Women” was 5.5. I only measured vertical force with the TLT boots, as rear Dynafit boot fittings are usually close matches across brands, and operate more simply than the toe system.)
“Women” spring has cutaway to reduce tension, interestingly it made little difference as opposed to releasing the boot with the heel unit disengaged, thus depending entirely on the toe unit.
Interestingly, when released with NO rear spring, I still got around RV 7 with the Cosmos and RV 6 with the Dynafit TLT-6, indicating how strong the Salomon-Atomic toe springs are in comparison to the weakest “Women” heel spring. More, and sadly, the toe fittings in my Cosmos test boots tended to catch during the release cycle and cause a spike. That’s an all too common problem you should always check for on the bench. A “sticky” boot is perhaps a non issue for skiers using higher RV settings (and might even be beneficial in terms of accidental release), but could be a factor if you’re seeking a smooth release at lower settings.
My testing indicates that no matter what, you won’t get a lateral release setting below about 6/7 for this binding (though that could vary depending on boot toe fitting action). Smaller folks take note. Since my testing indicates the various springs are actually providing a fairly limited range of values, there is no reason for more springs within the range. That explains why these bindings work well for so many people. In other words, if you’re seeking a an RV value setting in increments of around 1 or 2, you get that with the three available springs. On the other hand, an additional super-high value spring could be a good addition. Conversely, if you desire torsional release values below 6/7 a different spring won’t help, you instead need a different brand-model binding.
Huge caveat with all this is your boot fittings are part of the binding, and can significantly change your release values. Thus, as I’m always harping on, if you desire accurate settings it’s necessary to test each specific boot-binding setup. Otherwise your are engaging in guesswork or at best trial and error (i.e., set binding low, ski it, eject, dial up, repeat) Brakes are a factor as well, if you use brakes they may change your settings and the ski should be testing with the brakes, since this project is about comparing strength of springs and getting an approximation of release values, I did not test with brakes.
Torque scale.
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Comments
29 Responses to “Measuring Release Values — Salomon-Atomic U-spring bindings”
Unrelated to post but what, if anything, do you use to plug up the holes left from removing the vestigial buckles?
I put a square of Gorilla tape on the inside, then fill with a gob of silicon caulk. Works fine. Lou
Hi Lou, you should use the A/T adapter for the Vermont device when testing most tech bindings. It moves the axis of rotation above the toe instead of the heel. But then again you have the torque arm coming out to the front instead of the rear which is typical when measuring alpine bindings. Also, you shouldn’t clamp the ski down for a twist test as you can unwittingly introduce off-axis force. Did you get a DVD with your kit?
Further, you should be clear whether you’re testing with brakes since the results can be very different (I don’t see them in the photo?). Finally, you should mention the BSL when backing into “RV” from Nm since the ranges are lumpy.
A real world data point…I skied the Salomon/Atomic pin binding all winter (80 days?) and never once released. I should also say there was never a point where I felt I should have released.
I’m 6’ and 190 pounds. Like steep/aggressive terrain but am a fairly smooth skier and don’t ski that fast. I used the Man spring with a 317 BSL Atomic Backland Carbon. I skied skis 95-107 wide. I’ve skied some very firm snow with my toe unlocked with no issues. Also I tour with the toe unlocked in soft snow which is a nice bonus. As Lou says the toe springs are pretty strong.
Hi JBO, everything I’m doing worked, am aware it can be tweaked. Main goal of my process is comparison between binding/boot combos, but it does measure the RV accurately enough in my opinion. Clamping the ski down is mandatory for what I’m doing, otherwise someone would have to hold it, same thing. Good point about brakes, no testing with brakes at this time. I’ll add verbiage about that. Thanks, Lou
Hmmm… different boots yielded smaller range of measured rv’s with the Dynafits than with the Salomon/Atomics. Super stiff toe springs make toe socket dimensions more critical?
I don’t totally get how clamping the ski can introduce “off-axis force” but a peg in front of the toe and behind the heel would seem like a reasonable approximation of the official VT Safety rig without requiring anyone to hold the ski.
I’d really like to see a post that looks at how brakes (with and without afd’s) effect lateral and forward release values.
Thank you for the insights. I tore my MCL and PCL in a forward twisting fall using these bindings this year. If I had fully understood the limitations of this binding design, or the significant force require for this particular toe piece, I would have switched to a more consistent releasing binding like the Vipec (what I ski now). All U-spring bindings have limits but this binding in particular has me pretty concerned for skier health and safety after three months of rehabilitation.
I’m guessing taking care to keep the wrench in plane with bindings minimizes “off-axis force.”
“(M)ore consistent releasing binding like the Vipec” meaning what? High toe spring tension is good for reducing prerelease which is good for skier health.
Talk about a blast from the past!. I used to have one of those analog torque wrenches about 40 years ago, but its a digital world now. “Vermont” must have found a bunch of these antiques buried in some farmer’s barn for 25 cents each.
If a device like this were to actually calibrate release torque it should have a bearing or collar holding the shaft in a constant position relative to the ski. Otherwise it measures torque plus off axis wobble as See noted .
See – Exactly re: off-axis force. Unsurprisingly the brakes affect the softer springs more than the stiff ones.
Lauren – Sorry to hear of your injury! Always sucks to miss out on ski time.
Unfortunately I don’t think you can conclude a different binding would have protected your ligaments.
I injured my MCL and possible ACL as well this season with a forward twisting fall with Vipecs and Scott Cosmos boots. I think, but do not know, that catching/friction between the toe pins and the sockets contributed to a catchy release, and to my injury. As Lou has frequently emphasized, I will from now on be checking my boots/bindings carefully.
Since you got this tool i am curious how a rad or vertical with brakes or other fully functioning adjustable bindings tests test out on a boot with a real dynafit fittings?
My opinion of fixed release/no brake bindings is they are for real rando dudes whom are dripping with lycra, otherwise the concept of compromising a binding that wasn’t that safe to begin with is silly
Thought I should emphasize the unlike a ski shop, I’m not using this tool to verify exact “DIN” settings for individual setups. Thus, so long as my results are repeatable it’ll suffice for comparing different bindings, evaluating the differences between U-springs, and that sort of thing (yes, including the influence of brakes). Rule of thumb with brakes, for our family, is they subtract 1/2 of a release value number in vertical retention, and add 1/2 in lateral due to friction and other types of mechanical resistance. I’d imagine in real life that might vary quite a bit per individual setup, and as Jbo say, the lower your settings the more influence the brakes will have.
As for measuring individual release values for a given shop customer’s boot/binding setup, the Wintersteiger Safetronic is clearly what you’d want, not some primitive system of levers and torque wrenches found “in a farmer’s barn.” (SMILE)
https://www.wintersteiger.com/us/Ski-Service-Rental-and-Lockers/Ski-Service-Machines/New-machines/Binding-Adjustment/238-Safetronic
Another thing: The best way to test is to have the “foot” and leg shaft fixed to a rigid metal frame, and move the ski, but such a setup is probably beyond the scope of what we could do here at Wildsnow. For example, I’ve seen the testing setup at Marker, G3 and Fritschi among others and they all use a large cubical frame with a fixed foot, with a ski and binding attached. Sometimes they’ll have a Wintersteiger as well.
https://www.wildsnow.com/15123/tech-binding-release-testing-acl-broken-leg/
https://www.wildsnow.com/19686/evaluation-test-tech-binding-release/
Regarding ACL/MCL and other soft tissue injuries, perhaps the Knee alpine binding does more to protect, but to the best of my knowledge ski bindings in general do little to nothing in terms of preventing such injuries by every mechanism with which they might occur. Regardless, touring bindings should be skied at the lowest settings possible without incurring accidental release, along with bench testing, and skiers should avoid falling as much as is possible… Personally speaking, I’ve had three knee ligament injuries while skiing. None required surgery but I’ve got one knee that’s not exactly 100%. One injury on early Marker alpine bindings that were locked up with ice (requiring one of my two Cascade toboggan rides), one on nordic racing skis while doing something stupid (something like “here, hold this while I try that”), and one on Silvretta 404 bindings during which I didn’t fall but simply twisted the wrong way while standing around in deep snow with a heavy pack. Lou
Xer, the Cosmos has “real” Dynafit fittings, what goes on is that fittings vary, even Dynafit certified ones, thus the importance of bench testing as well as knowing that wear on the toe fittings can perhaps make them operate more smoothly but may also lower the release values. Lou
Sorry if I sounded curt, LDL. Obviously you’re saying that you believe the Vipecs release more consistently. But I’m wondering if there is evidence, anecdotal or otherwise, that supports claims of superior release performance with Vipecs. Also, I am very interested if the U-spring system is causing people to ski with their bindings at suboptimal release values, perhaps too high in your case? For example, if I use the M springs on the mtn/backlands, my bindings will (theoretically) be at the same release values as Chris (above), who is bigger, younger, stronger and more skilled than I. (My boots are a lot smaller, so there is that.) I’m glad the rehab apparently went well and you’re back in action.
I’d be interested if you could make some measurements on the new Black Diamond(ATK) bindings when they come out. In particular the fixed release/replaceable spring bindings like the Trofeo. I’d like to know if the numerical RV’s correlate to dynafit adjustable numeric values
Non dynafit fittings got garmont/scott in trouble back about yrs ago, we compared a buddies cosmos and there was a very real difference
,I always arrive at my binding setting by turning them up till they stop falling off
Dynafit din like settings end up being about the same as my din alpine setups
Agree
Hey all interested in this, I should mention that as was alluded to above, how the ski is clamped does influence release values, especially vertical. For example, if the ski is fairly flexible and clamped in a way that allows it to flex, the boot pulls a few mm forward on the heel pins as the ski flexes during a forward release, thus reducing the release values.
I mention this as I want to emphasize that any testing I’m doing is to simply determine the ball-park release values, and how they compare between brands and swapped springs. It’s debatable, but I believe the Vermont system is not adequate for determining *exact* value under the DIN/ISO standard, for example if serving a ski shop customer. A Wintersteiger machine is clearly what you’d need for that.
Lou
Seems to me that if you place the clamp close to the heel piece for vertical testing, the problems posed by ski flex would be minimal. And I am not aware of any other source of this sort of transparent, measurement based information available to those of us who don’t have access to expensive shop equipment. If you’re lucky enough to have access to a shop that is up on this stuff, that’s great. But I suspect such shops are rare. Thanks again, Lou.
Indeed… main point is that bench measurements may not be the same as real life, and also that classic tech bindings have more than one flaw as to their release-retention characteristics. As someone said “they’re a ski touring binding, not a ski binding…”
All the more reason to learn about the strengths, weaknesses, quirks, etc. so as to reduce the risk of having an equipment related bad day.
Agree! Perhaps part of the reason WildSnow.com exists (smile). Lou
Hi Lou, the Vermont tool can be fairly accurate if you keep it calibrated and use the Vermont vise. But the machines are more fun. With your hands free you can record releases, slow down the video and see some interesting behavior!
The Wintersteiger isn’t my favorite for tech bindings fwiw. You have to put the ski in backwards for lateral tests and there isn’t a calibration to adjust for the vertical axis of rotation being further forward in tech boots.
Jbo, which machine do you think is best? Thanks, Lou
Hey Jbo, can you give me a center to center measurement for the add-on “pivot change” bar that’s supposed to be used for AT bindings? I can’t afford to by one, but I have a welder and some old tool junk laying around, so I’ll cobble one up so I can eliminate the variable of my not using it. Thanks for any help. Lou
No problem Lou, it is 10 3/4″.