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Binding lift problem

post #1 of 12
Thread Starter 
Hello, I am new to these fourms and I am having a little trouble trying to solve my binding problem. I remember reading something in the ski magazine about having to much lift in your binding causes knee problems especially in powder. I searched on the fourms but could not find any information. What I was wondering is this statement true and could I be effected by it? I ski on bandit b2 2005 model with marker 12.0 glide control. When I first got the bindings installed on the b2, I was worried that there was to much height in them. But I could'nt find any info on what the side effects were with to much height. My last day skiing in alta I felt some pain in my knee. I was skiing crud and powder all day and I was wondering if the pain in my knee was do to some of the binding height. If anyone could please inform me on the effects of lift height it would be greatly appreciated.

Matt
post #2 of 12
Thread Starter 
"bump"
post #3 of 12
Powders skis tend to work better mounted flat without lift. How this is related to knee problems? I cannot see how 10mm or so of lift could cause knee problems especially after just one day of skiing.
post #4 of 12
Funny you brought this up. I asked another question and in a reply was mentioned "no risers/plates/tracks. Easier on the knees...". Never thought about it. 6-10mm lift - probably not a big deal. Demo bindings, Marker glides...maybe?

http://forums.epicski.com/showthread.php?t=42422
post #5 of 12
I think that no plates or risers are harder on the knees. By using a riser, you effectively narrow the ski. A narrower ski applies less torque to the knee.
post #6 of 12
Quote:
Originally Posted by BigE View Post
I think that no plates or risers are harder on the knees. By using a riser, you effectively narrow the ski. A narrower ski applies less torque to the knee.
....but a riser creates more of a lever (leverage).
post #7 of 12
Quote:
Originally Posted by NE1 View Post
....but a riser creates more of a lever (leverage).
But the foot has to move farther to apply it...
post #8 of 12
Thread Starter 
Thanks for everyone's post. I found the skiing magazine where they mention the problem. Its the Gear Guide 06 issue in the Big mountain pro/custom section. It says "In powder, too much lift height strains your knees, so most big mountain boards come "flat": without plates or binding systems". Is this statement only true for big mountain skis or all skis in general, because I only have B2 and those are considered all mountain skis.

Matt
post #9 of 12
It's true of most off-piste skis, whereas most on-piste skis perform best with fully integrated binding systems. B2's are really right in between both categories, but edge to the off-piste side of things, hence a flat deck binding. Rossi Zenith are very similar in dimensions, and intended use as an all around all mountain along with the B2, but edge to the on-piste side of things, ergo a system binding.

There are certainly exceptions to this, but as a general rule of thumb: on-piste=plate/system, off-piste=flat deck.
post #10 of 12
Quote:
It says "In powder, too much lift height strains your knees, so most big mountain boards come "flat": without plates or binding systems".
I can't see how that statement holds up biomechanically? Perhaps someone could explain?

The effect of a lifter/plate is to reduce the amount of torque on the ankle, so comparing a ski with and without a plate - for the same amount of knee angulation the ski with the plate would have a better edge hold.
post #11 of 12
I see at least two separate issues here:

1. For the same edged angle, the longer lever requires greater vertical motion.

To help visualise pivots and things:



Notice that's true of all skis, irrespective of ski width. If that vertical motion has to come from the joint that also provides frontback balance and absorption. . .

Advantage - flat ski

2. Leverage required to achieve any given edge angle (a function of ski width). Back at the graphic I posted in the thread "Riser plate or not on powder skis"



Since the pivot point is at the edge to be set, there is a variation with ski width.

Advantage - lifted ski.

For me, the two factors combine in such a way that I like ~12mm lift on a 100mm-waist ski.
There are other very good descriptions of contributing factors and personal preferences in that thread, for example #21 where Physicsman points out the need to compensate for random rotary torques (which are also related to ski dimensions).
post #12 of 12
Living in the mid-atlantic, I haven't thought about this issue much. When I go out west, I just deal with what I have or rent what I can.

But one thing that seems to jump out at me... Powder skis, with waist widths of 100mm or more would seem to benefit from lifters. It would ease the lateral torque on the knee, because the width of the ski is trying to flatten it when you aren't on ("in" to be more precise) snow that is deep enough that you are always creating your own platform. Said another way, as soon as the ski contacts a surface that wants to flatten the ski, it would put tremendous lateral force on the knees. Lifting the boot off the ski effectively lessesns that force. So if you were skiing in crud, as was mentioned by the OP, I could see where adding lift would actually help. My guess is that his knee pain from skiing that day probably came from the rotational forces he used in the powder and crud, as opposed to a stack height issue.

Sorry to say it... but I think it's more likely to be operator error than an equipment issue that led to the knee pain.
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