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Bindings Affected by Temps?

post #1 of 23
Thread Starter 
6 weeks ago, on an ultra-cold day at Keystone, a buddy from California demolished his right knee when his binding, set at DIN 7, didn't release in a twisting fall. I wonder if the non-release could have been due to the extreme cold.

Regardless of settings, don't cold temps increase friction in mechanical devices?

His knee was virtually destroyed; ACL severed, MCL torn and detached from femur, PCL torn, medial meniscus ripped, and tibia multiple fractures with bone chips. They almost had to amputate the leg due to fluid and blood build-up and infection. He'll never ski again. A nightmare.

This experience spooked us. I think about this every time we ski in cold temps.

The binding was 1.5 year-old Atomic Neox 4.12, which previously worked well.
post #2 of 23
I don't know anything so i'm just guessing but if water got inside the spring couldn't it freeze?
post #3 of 23
DIN 7 is not that tight - are you sure his forward pressure was set correctly?
post #4 of 23
Thread Starter 
Quote:
Originally Posted by PhilT View Post
I don't know anything so i'm just guessing but if water got inside the spring couldn't it freeze?
I'm clueless in this area. Wouldn't the binding vendors guard against water thaw and freezing?
post #5 of 23
Thread Starter 
Quote:
Originally Posted by redkal View Post
DIN 7 is not that tight - are you sure his forward pressure was set correctly?
I don't know how they were adjusted. He bought the skis, Metron B5's with bindings from his local dealer who did the work. I still have the skis at my house, and could have them checked (he'll never use them again).

I just wonder if the bitter cold could have increased friction to the point that normal settings are skewed.

Doesn't temperature affect friction?
post #6 of 23
Really sorry to hear about your friend!
Here's to a speedy recovery!

Pure cold affecting the bindings?..I very much doubt it. Re-test sure..but to To re-test under those condtions you would have to do it when it was that cold again.

Snow in the binding and freezing?. I doubt that unless by chance there was already snow in the binding..packed in and or frozen..or almost and he got in ok and skiied for a long time possibly with more snow added that froze too.

I guess that could happen. The binding gets really loaded with wet snow..maybe the consistency of slush then In goes the boot,temps plummet,maybe some new snow added and it is all frozen. Could..but i doubt that.

I skiied last nite in some brand new Atomic's. (Older 6-14.)((500 lbs)) It started to drizzle. How nice. Then the temp started to plummet. Nicer. Then freezing and freezing rain. I sure wasn't out long in that before I came back. Sure I could see that there was ice on/around the bindings. I was wet/frozen jacket and wanted to get back to where my car was. I should really have bailed into the nearest lodge.
It was really hard to press the heel release down. Understandablly. Then it was really,really hard! to,lift my boot heel up to lift the heelpiece up to get out. Even when they did sort of release it did not feel good..normal.
I can't fault the binding..or any binding in that case.
I put the skis back in the car which was still somewhat warm. The rain/freezing rain ended and it got colder. Obviouslly the binding/mechanism was still soaking wet. I decided to test them..see if the GS11's could come back out.
They were fine when wet and not cold.. right beside the car.
I tested them again before and after I got on the lift.
Then a few more times.

I'm sure that by putting them through their range of motion and not being in the rain that most of the water was displaced.
post #7 of 23
Quote:
Doesn't temperature affect friction?
No, not generally. At least that's what high school physics said!

Thermal expansion/contraction of the parts/hinges in the binding could be an issue at extreme temperatures, though. If it was cold enough, the binding might lock up and not be able to release smoothly. Ski bindings should be designed to still work effectively at pretty cold temperatures, though.

Or, as mentioned above, snow/ice jamming the mechanism. That is definitely capable of causing problems. Usually the issue there is that you can't get into the binding if it's frozen or jammed.
post #8 of 23
Binding releases are taken care of by springs... metal springs.... When metal gets cold, it gets stiffer IIRC. May require more force to release, but not sure how much... I could see this issue though... when the bindings are set it is probably room temp... 70F... then bring them out into freezing temps.. it's a pretty big differential.. Not sure how that would affect on-the-hill performance.

I suspect it was the manner of the fall and not the bindings.. bindings are not made to release in EVERY direction under EVERY force... He may have found one of the falls that don't cause the bindings to release..

If you give some more details it may help... temperature (other than ultra cold), speed (slow or fast fall), weight, etc...
post #9 of 23
Thread Starter 
Quote:
Originally Posted by hydrogen_wv View Post
Binding releases are taken care of by springs... metal springs.... When metal gets cold, it gets stiffer IIRC. May require more force to release, but not sure how much... I could see this issue though... when the bindings are set it is probably room temp... 70F... then bring them out into freezing temps.. it's a pretty big differential.. Not sure how that would affect on-the-hill performance.

I suspect it was the manner of the fall and not the bindings.. bindings are not made to release in EVERY direction under EVERY force... He may have found one of the falls that don't cause the bindings to release..

If you give some more details it may help... temperature (other than ultra cold), speed (slow or fast fall), weight, etc...
Thanks to all for the helpful comments.

With wind-chill, we were in the -20's - extremely cold.

It could be that temperature had nothing to do with the horrific outcome. If not, I'll worry less about my binding settings.

He was skiing a mild slope - Mozart on North Peak. He simply skied up a bank (like a halfpipe) and then tried to turn back down. He crossed his tails while on the bank, thus preventing his skis from following the down-slope direction of his body.

Something had to give, and it was his knee. He heard a "pop" like a champagne cork (the ACL breaking), and crumpled onto the snow.

If such cold doesn't materially affect binding performance, I chalk it up to an unlucky, nasty twist that couldn't be accommodated by the binding. As you said, bindings can't release in every direction, in every fall.

If so, I won't worry about my binding setting in sub-zero temps.
post #10 of 23
sorry to hear about your friend.

unfortunately, bindings don't always release when they are supposed to. Setting the bindings based upon skier info helps to minimize the possibility of such injury but in no way dimishes the risks. I've seen skiers at every skill level, and every DIN setting have release issues that destroy their knees. I would have an independent shop test your friend's bindings and boots set exactly as they were at the time of the injury. It is possible that the binding has a problem and a simple torque test would let you know. It wouldn't be the first time Atomic had binding problems
post #11 of 23
That's terrible, it really is every skier's worst nightmare. Just goes to show how you can never take your bindings for granted.

Did he happen to drive to the area with his skis unprotected on top of the car?
post #12 of 23
A -20 windchill can occur at relatively warmer temperatures, depending upon the wind itself. I wouldn't consider that a real factor. I'd expect that something else compromised the release, such as aforementioned packed-in snow altering forward pressure or boot condition contributing to unexpected friction.
post #13 of 23
Thread Starter 
Quote:
Originally Posted by mudfoot View Post
That's terrible, it really is every skier's worst nightmare. Just goes to show how you can never take your bindings for granted.

Did he happen to drive to the area with his skis unprotected on top of the car?
Yes, it was a horrific injury, which still spooks me - hence this thread, and my concerns.

It seems the consensus of most here is that low temps shouldn't be a factor. I suspect it was just a bad fall, at the wrong angle.

I suppose it's the risk we all take. But, to see it up close, with a friend, is unsettling. He'll walk again, but never as he did. His life is changed.

Regarding the skis, we put them inside my Outback. I never place unprotected skis on the roof. I-70 is a messy road. All that sand, salt and grit can't be good for bindings.

I'll always have a torque test done, henceforth, anytime I adjust my bindings.
post #14 of 23
Quote:
Originally Posted by Captain_Strato View Post
With wind-chill, we were in the -20's - extremely cold.
That is not extremely cold. I've skied in temps that cold without windchill this season. Actually, on one cold night I did wonder if one of my bindings wasn't releasing properly when I did my usual twist test and my foot didn't come out. Torque tested them the next day and while that binding passed, it did so at the high end of the range and with noticeable notchiness on the bench. Junked that toe.

A coil spring is given by:

k=(Gd^4)/(8nD^3)

k=rate
G=modulus
d=wire diameter
n=number of active coils
D=mean diameter of coil

G for steels varies by something like 2 percent over the entire temperature range you could conceivably ski in.

Note that the ISO standard allows +/- 15% for torque values in routine testing.

The springs are not likely the issue. The plastic parts, clearances, water drainage issues, boot sole, etc. are all a lot more interesting questions. Most of us have seen old boots break in cold weather. I've seen bindings break in both cold and warm weather.

Chances are very good that your friend's horrible outcome had little to do with the binding, at least in the sense that the binding functioned as designed. That said, I think it is wise for people to release check their bindings frequently. If you can't twist out of your toe without undue effort and your settings are reasonable, you should look into it...and you should also perform a check on the bench at the beginning of every season minimum.
post #15 of 23
In my much younger days as a macho ski patrolman in Montana we used to twist out of our bindings every time we got out of our skis (everyone was using Look turntables). It was a constant check on your bindings and your manhood. It was damn cold a lot of the time and I don't remember any temperature related problems.

I am very anal about always brining my skis in, drying the edges, and leaning them against the wall bindings down to get the water out every night, but a slow twisting fall can take anyone down. We used to have an old joke about always ski fast, you'll always come out of your bindings. Stupid, but maybe with a little truth.
post #16 of 23
Thread Starter 
Garrett: Great reply, with insightful comments.

Minus 25, for hardy types, may not be cold. But, to me, 50 degrees below freezing is painfully frigid.

Regardless, binding checks have gone from barely on the radar, to my #1 priority in equipment maintenance.
post #17 of 23
To be clear, I didn't say that to be macho, but to point out that this is a temp that ski bindings are AFAIK not adversely affected by. An "extreme" -50 day might bring up some interesting issues...most likely with plastic parts...but I don't know anywhere to ski that gets that cold and still runs lifts. (thankfully. )
post #18 of 23
Quote:
Originally Posted by Garrett View Post
T
A coil spring is given by:

k=(Gd^4)/(8nD^3)

k=rate
G=modulus
d=wire diameter
n=number of active coils
D=mean diameter of coil

G for steels varies by something like 2 percent over the entire temperature range you could conceivably ski in.
That's all we really need to know. Not the bindings fault, just the way he fell.
post #19 of 23
yup, i just posted the rest of the jazz so people could see the linear relationship between the modulus and the resulting rate.
post #20 of 23
The cold may have had a greater affect on the muscles and tendons of the skier.
post #21 of 23
Quote:
Originally Posted by Ghost View Post
The cold may have had a greater affect on the muscles and tendons of the skier.
Does the temp of your pieces parts change that much when it is cold out if you are dressed well/not hypothermic? I have no idea.
post #22 of 23
Being not properly warmed up does increase risk of injury. I imagine if you are cold, it's harder to get and stay "warmed up".
post #23 of 23
Sounds right. Never really thought of it that way but I definitely do find it harder to get loose and warmed up when it is really cold out. Probably a much bigger deal than the equipment.
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