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Bruno Schull

Getting off the lift
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Aug 24, 2017
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Hi. This goes out to all the folks out there who have experience testing bindings and release values.

How common is it that a binding/boot system will produce release values other than that at which the bindings are set? For example, say one sets the release value to "7." How common is it that a binding will release at significantly above/or below that setting, and therefore require adjustment to perform within the specified range?

Another way to ask this question is, "How sensitive are bindings to different boots/conditions? If you set up and adjust a binding to one boot, and then set, test, and adjust the release value correctly, and then set up the binding for another boot, is it common that the release values will need to be adjusted again to accomodate the slightly different interface of the new boot?

I ask for the following reason: I have a ski touring set up, and I read with interest a study published in the superb Skialper buyer's guide from Italy. The study showed that the great majority of touring bindings (pin bindings or tech bindings) 1) Do not release anywhere near the set values, and 2) perform very differently with different boot and pin combinations. I am aware of the differences between touring bindings and alpine bindings, and I am not surprised by the results, except perhaps by the uniform and substantial inconsistency across brands and models. I think the interface of pins and sockets makes this inevitable.

I would simply like to know if the same or similar inconsistency is seen in alpine bindings--I suspect that there is some variability, but not nearly as much as with touring bindings.

Thoughts?

Bruno
 

Winks

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Hi. This goes out to all the folks out there who have experience testing bindings and release values.

How common is it that a binding/boot system will produce release values other than that at which the bindings are set? For example, say one sets the release value to "7." How common is it that a binding will release at significantly above/or below that setting, and therefore require adjustment to perform within the specified range?

Another way to ask this question is, "How sensitive are bindings to different boots/conditions? If you set up and adjust a binding to one boot, and then set, test, and adjust the release value correctly, and then set up the binding for another boot, is it common that the release values will need to be adjusted again to accomodate the slightly different interface of the new boot?

I ask for the following reason: I have a ski touring set up, and I read with interest a study published in the superb Skialper buyer's guide from Italy. The study showed that the great majority of touring bindings (pin bindings or tech bindings) 1) Do not release anywhere near the set values, and 2) perform very differently with different boot and pin combinations. I am aware of the differences between touring bindings and alpine bindings, and I am not surprised by the results, except perhaps by the uniform and substantial inconsistency across brands and models. I think the interface of pins and sockets makes this inevitable.

I would simply like to know if the same or similar inconsistency is seen in alpine bindings--I suspect that there is some variability, but not nearly as much as with touring bindings.

Thoughts?

Bruno

It depends on the age of the binding, the plastic and the metal, each have a shelf life and a time span that just happens to deteriorate. Also with frequent use, in & out a lot these things wear down.

Next question being how sensitive they might be to different boots, it is quite a lot. Every boot is measured different, I don't care what the millimeters say. Everything has its own quirks.

Boots and bindings should be checked every time the original set is not used. "My friend has the same boot size" Does not mean it will work perfectly.

Pin bindings are a entirely different subject. Those are extremely sensitive to even the smallest screw turns sometimes. The toe also does not have a set release value at all on most pin setups.

No bindings, even bindings within the brand are consistent with one another. Its all about spring tension and nothing is exact. That is why we test bindings and have them tested at least once a year.
 

Brra

In the parking lot (formerly "At the base lodge")
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If both the bindings and the boots are from the 00s and onwards it is very rarely an issue. At most it differs one step on a demo binding. Some manufacturers tend to be wide in the front (Tyrolia, Marker) others tighter (Look).

The DIN setting is not relevant to the boot when the boots fit properly. If they are too loose or too tight, it will release early or in some cases not release when they're supposed to. It's also important to make sure the boots/bindings aren't covered with ice or snow, which sounds obvious but in 90% of cases when people come back complaining that their rentals don't fit that's the issue.
 

pchewn

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The ACCEPTABLE range of release torque tolerance is 10% from the DIN standard.

For example, if your toe binding is set for an indicated value of 6. The standard says the toe release torque should be 50 N-m When tested, the boot/binding system allowable range is 45 N-m to 55 n-M

In practice, when the bindings are set at 6, they release at 6 (+/- 10%) nearly always. It's that "nearly" that the test is designed to catch. (Worn boot soles, AFD worn out, improper forward pressure, etc.......)


(The above applies to downhill boot/binding system, not to AT pin type)
 

Slim

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@pchewn , I haven’t looked up the standard, but why would the AT binding norm be any different than the alpine binding norm as far as allowable variation?
 

Slim

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@Bruno Schull , Jeff Campbell’s Research also found that minute variations in dimensions made a huge difference in release with tech bindings.
All the more reasons to test bindings.
 

pchewn

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@pchewn , I haven’t looked up the standard, but why would the AT binding norm be any different than the alpine binding norm as far as allowable variation?

I'll speculate on some reasons why the AT standards might be different than the alpine binding standards. (Speculation)
  • The AT standards are newer and the manufacturers might need time to develop and test to a more stringent standard.
  • The AT binding manufacturers need additional leeway in the spec in order to save cost/weight or touring capability
  • The AT boot/binding interface (pins) is technically harder to achieve the 10% tolerance
  • The AT bindings don't have a DIN indicator, so the only "indication" of the release setting is an actual test
All speculation because I know little if anything about AT-specific equipment. I'm just guessing
 

Slim

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I would assume that AT bindings that are certified have an indicator. Only one I have in hand is the Vipec and it does.
 
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Bruno Schull

Getting off the lift
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Aug 24, 2017
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Compared to the alpine binding world, the touring binding world is the wild west.

One problem is that, before you have a standard, you have to standardize something.

Off the top of my head, there are at least 5-10 different kinds of touring bindings, with extremely different functional elements and mechanical operation. I'm not taking about brands of bindings--there are many different brands--I'm talking about different binding designs.

Add to that the fact that most touring bindings rely on metal pins inserting into metal holes or slots to fix the boots to the skis. As the studies mentioned above indicate, very small differences in tolerances between these metal parts can have very large effects on retention and release, more so than plastic surfaces sliding or rolling on each other, as with conventional alpine bindings.

To return to the study conducted by Skialper (Italian), what it showed is that nearly all touring bindings released at values very different from the values marked on the housing (if they were marked at all). Moreover, the bindings released at very different values depending on what kind of boots and pin systems are used (Masterfit, Quickstep, and so on). And this, of course, is in "perfect" laboratory conditions. Load the ski, twist the ski, change the temperatures, add snow, ice, mud, or bits or rock, and all bets are off.

Note, the study did not say that particular binding and boot combinations did not release at a consistent values--if they tested a particular binding and boot combination 10 times it might have released at the same value each of those times--but the release values were usually not anywhere close to the specific/predicted values, with one or two notable exceptions.

Ski these bindings at your own risk (or at the risk to your own knees and ankles).

That said, there is strong evidence that touring bindings that release laterally at the heel do a better job of protecting your knee ligaments in twisting falls, while alpine bindings that release laterally at the toe do a better job of protecting your tibia.

One can go deep down the rabbit hole with binding release function--touring or alpine. My question was simply to have a basis for comparison--what kind if release value variation is tolerated in alpine bindings?

Thanks for the contributions.

Bruno
 

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