ski binding tension question
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KevR
December 14, 2005
Member since 01/27/2004 🔗
786 posts
Recently i was testing out my ski bindings for the year (in the living room), and noticed that when clicked into them, if I lean forward slightly (but firmly) the release lever on both skis flexes downwards and the heel of the ski boots lifts up slightly off the binding platform.

In essence it's kinda like a half-release from the binding... but not a full release, the boot is still in there tight but the heel has come up a bit (maybe 1/4 inch or so, it's a little hard to tell really when in the skis)

With effort I can pop out of the bindings with a very strong forward motion but it's not easy which is fine; i mean one does want to pop out right?

Anyway -- the question is -- is this correct? Or should the binding not really allow the heel to come up at all with even a hard lean forward? (which is what I think)

I suppose it is worth noting that I've never had an issue with the bindings pre-releasing while skiing, and the bindings are set to about 5.5-5.75 ...
warren
December 14, 2005
Member since 07/31/2003 🔗
485 posts
Kevin,
The DIN setting is of course based on your height, weight, and skiing level. I'm 5'6", about 165-170 lbs and a type III. My bindings are set at a DIN of 8. I know they release when I need them to as in Whistler I went over the front of my skis in a crusty snow mogul field and they popped right off! Generally, there is some play before there is release. There are DIN charts online to see if your setting is in the right ball-park. If you don't feel comfortable with the behavior, I would take them to a shop and let a qualified technician do a release check for you.

-Warren-
kwillg6
December 14, 2005
Member since 01/18/2005 🔗
2,034 posts
To echo warren's comments, the din should be set for weight, skier type, and how aggressive you ski. The movement you speak of may be due to the wear of the boots if more than one season old, or may be the actual binding's characteristics. I have some play in my bindings which is good when there is some snow packet to either boot or binding when step in is performed. I would have concern if, when you lean to the tips of the skiis, your binding releases. Both toe and heel piece should be adjusted accordingly. If you aren't sure of how to adjust them yourself, take them to a certified binding mechanic and have them checked/adjusted/lubricated prior to too many runs.
KevR
December 14, 2005
Member since 01/27/2004 🔗
786 posts
I have been told by a ski-instructor friend that the 'play' as i described it, is not actually play but a built-in feature of modern bindings which allow for the heel to come up slightly when leaning forward (or applying a forward pressure is maybe more accurate). Play itself is not actually good and would mean the bindings or boots are over worn, which as one might suspect would be dangerous for correct binding release characteristics...
Now I just need to figure out if i can increase the load at which this occurs as the current settings seem too light to me, and the effect too easy to achieve...
comprex
December 14, 2005
Member since 04/11/2003 🔗
1,326 posts
Quote:

the heel to come up slightly when leaning forward (or applying a forward pressure is maybe more accurate).




If one is applying forward pressure through the leg muscles that control bending of the ankle and not through motion of the CM, is there any reason for the heel to come up?*

*(relative to the CM or ski, not toe)
JohnL
December 14, 2005
Member since 01/6/2000 🔗
3,518 posts
Quote:

Quote:
--------------------------------------------------------------------------------

the heel to come up slightly when leaning forward (or applying a forward pressure is maybe more accurate).


--------------------------------------------------------------------------------



If one is applying forward pressure through the leg muscles that control bending of the ankle and not through motion of the CM, is there any reason for the heel to come up?*

*(relative to the CM or ski, not toe)






Did PhysicsMan steal your password?
comprex
December 14, 2005
Member since 04/11/2003 🔗
1,326 posts

He's had far more practice at phrasing things better.

You forgot: "Sweaty tree skiing"
KevR
December 14, 2005
Member since 01/27/2004 🔗
786 posts
I think CM probably changes regardless of lean or lower leg angulation on the slopes, even if its slight. On the carpet you may be able to contort yourself so that it may seem like it is not so, but while skiing you'd probably not want to sit back, and even if you were sitting back a bit and thought you were just flexing your lower leg forward, my feeling is in all likelyhood your upper body is reacting as well and overall CM is changing. if you are sitting back enough, then no your heels would stay put largely although -- again it seems like to me there's some unloading on the heel -- and this may show up at the binding. If you are balanced over the skis, i'd guess there'd definitely be some unloading of the heel - you know i have thought skiing was more of a ball-of-the-foot sport although this is somewhat counter-intuitive ... Thinking about quick changes of slope towards more steepiness, you'll almost always pitch yourself forward enough to unload the heel some, to quite a bit... I think this is definitely true for groomed slopes where shovel bite can be aggressively applied. On powder, hmmm ... my experiences are limited enough that i can't even speculate very well, i've never really skied in bottomless powder at high speed, only about 2-3 ft with fairly firm snow below it... i only remember letting the skis turn and not forcing anything like i tend to do on groomers, still there is an unload between arcs. ...just trying visualize it all...
Crush
December 14, 2005
Member since 03/21/2004 🔗
1,021 posts
KevR - most binding allow for some elastic movement in more than a few directions. While Rossi turntable binding are pretty solid on the heel the tow allows for some elastic defection. Marker allows toe and heel deflection before release. The heelpiece may lift a tad, but you are probably ok because latterally your heel is not going anywhere. a 5.5 setting is not that heavy so even though the heel spring is preloaded, it will deflect a little .. it's not like you are running greenspring bindings. You should be able to lean waaay out over the tips of your skis like a bowspirit and not have a release.

I personally crank my heel piece DIN setting ~1.5 higher than the recommended setting (at 140 lbs and a III+ it is usually around a 7,5-8 but I put it on 9 usually) but that is just me and I NEVER recommend it to anyone. On my big-mountain skis I do set the binding to 10 because in most situations it is better they stay on than come off, again I would NEVER recommend it unless you are doing a lot of no-falls stuff.

But definitely, when in doubt, have a binding tech do a load test on 'em.
double_agent
December 26, 2005
Member since 10/27/2005 🔗
4 posts
The "play" you refer to in this post is called elastic travel. All brands of bindings have some built into the toe and heel piece. In fact, there have been performance arguments about how much elastic travel a skier should have. It is true that your height, weight, age, skier type AND boot sole length all account for the selected DIN number. The travel acts as a shock absorber of sorts, this way as you torque the binding (either by twisting or upward load) you have a little give before releasing from your bindings. It's so the things don't act like a light switch either being on or off. As most everyone has mentioned, let a certified tech at a shop set and test the system with your boots.
KevR
December 26, 2005
Member since 01/27/2004 🔗
786 posts
I will probably get my bindings checked just to make sure they are set the same in real-force... i turned them down from whatever the original recommendation was for my size and ability a few yrs back. basically i've a screwed up knee, so i thought -- hmm, well if i never pre-release, ... anyway, no problems so i kept them light.
however now i realise that maybe they can be too light though. i am thinking the binding elasticity or whatever you'd like to call it adds a little hysteresis in things... maybe a bit tighter would be better! More responsive right? anyway, a little experiement but still it will be on the light side for me I think.
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