Skiing Ability vs Binding Placement
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rmcva
November 5, 2007
Member since 01/28/2004 🔗
187 posts

Thought this was interesting - where to mount bindings and their impact on skiing:

http://www.techsupportforskiers.com/binding_placement.htm
comprex
November 5, 2007
Member since 04/11/2003 🔗
1,326 posts
Old news really.

Find a large enough dowel and make your own teeter version of the balancer.
Denis - DCSki Supporter
November 5, 2007
Member since 07/12/2004 🔗
2,220 posts
How is it that the Campbell Balancer finds the center of the running surface? I have never understood this.
KevR
November 5, 2007
Member since 01/27/2004 🔗
786 posts
no, that's interesting! I've often felt i can't get FORWARD enough on my skis. I really have to work abit to keep ahead of the dang things... well that's the way it feels. I've thought to myself: i wonder if i just moved my bindings up a bit, what would that feel like?

Well i have Markers and K2 mods (yes now ancient model-t like skis but they still ski pretty nice i think)

Anyway -- 'spose i could just skootch 'em up a notch if i get the gist of this article and give it a try.

Well except no snow, but I mean when there is some ...
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comprex
November 6, 2007
Member since 04/11/2003 🔗
1,326 posts
Denis, it doesn't.

It finds which part of your foot,

( when placed in a ski boot, ramped forward with foodbeds and miscellaneous wedging gizmos shoved under it)

is to be mounted on the center of running surface.


It's a funny game to play. Notice that the article talks about measuring not one but 2 quantities, center of running surface (CRS) which is completely independent from the skier's balance point measurement. The factory assumes the skier's balance point is dead center in the boot.

I usually come out 1.5-2cm forward of the boot-center point, not surprising in a skater really.

I know very feminine-shaped women who come out dead-neutral and some quite, ah, androgynous ones who prefer to be 3 cm forward.

About the greatest success I've had with the balance point-to-CRS system is in mounting ca. 1996 i.e. straight, SL skis.

There is really too much going on with both the flex of powder skis and the sidecut of shaped carvers for me to absolutely believe in Center of Running Surface mounting. I've screwed up 3 pairs of my own twintips, 2 pairs of my own powder skis, and at least one pair of race carvers this way.

The balance point determination is still roughly useful though, particularly if I'm not using Railflex/Neox/Xentrix with the sliding feature.

The name of the game then is balance point offset from factory marked center, not balance point to CRS.

KevR
November 6, 2007
Member since 01/27/2004 🔗
786 posts
If ski manufacturers use center of boot as the "balance" point -- and this is true as you suggest. Then this WOULD NOT be ball of foot -- and indeed verifies in my mind that they mount the bindings back a few centimeters from what some consider the ideal location of the ball of the foot area as being the true 'balance' point.

I think one huge problem besides trying to feel like you are skiing more on the ball-of-the-foot which no doubt for many would make little sense -- since again, i bet most casual skiers tend to sit back anyway on their heels...

-- Is trying to figure out where the ball of the foot is in the boot.

This is not going to be easy although the boot, properly sized to the foot will give some indication.

Even if the "balance" point is found, either dynamically or statically -- it's still an ideal that may not fit the way you've skied for years... even if its "right".

STILL -- the point seems to be that you may sit back more in your skis because the bindings put you back there -- and thus perhaps the location of the bindings is yet another area to consider in ski tuning...

Well, great, just what we need -- another variable! :-)
comprex
November 6, 2007
Member since 04/11/2003 🔗
1,326 posts
 Originally Posted By: KevR
If ski manufacturers use center of boot as the "balance" point -- and this is true as you suggest. Then this WOULD NOT be ball of foot -- and indeed verifies in my mind that they mount the bindings back a few centimeters from what some consider the ideal location of the ball of the foot area as being the true 'balance' point.


I'm not sold on the whole 'ball of foot' idea as classically stated, not because I think it is wrong, but because it is over-complicating the issue, particularly when you consider the role of the arches of the foot, and how people vary.

 Quote:

-- Is trying to figure out where the ball of the foot is in the boot.

This is not going to be easy although the boot, properly sized to the foot will give some indication.


I don't bother finding the ball anymore or anything else that requires transfer of internal to external dimensions.

It is easy as pie to find the external balance point, if you size the dowel right. With a 3 inch dowel I reckon you can get to within 2mm.

Smaller than that and the action is too "fast" for the balancee to be precise with foot placement i.e. you're measuring teeny differences; much larger than that and the balancee starts getting nervous without poles or an external bar.

All IMO, of course, and I should say I've only done about 10-12 of these for myself and friends.

 Quote:

Even if the "balance" point is found, either dynamically or statically -- it's still an ideal that may not fit the way you've skied for years... even if its "right".


I think you'll find that, if you have found the balance point, and your boots allow you to flex in a full range of motion whilst at that balance point without levering against the skis, all the rest will adapt eventually.

One "existing technique" point that is not addressed in the article is taper angle and sidecut depth. On skis that do not have very large taper angle, or that have a small-radius sidecut, or both, moving the bindings forward will cause crossing of tails unless the skier is really careful with their stemming moves. This is how I kecked up my twintips and made them useless in bumps. They carved up a storm, tho.
KevR
November 6, 2007
Member since 01/27/2004 🔗
786 posts
The ball-of-the-foot thing -- well you know, its someones ideal. Maybe it makes sense but you are in a boot -- not a cycling shoe.

ANYWAY -- it seems to me that what one really needs is some sense of the "perfect arc" (and we are talking about carving here right?) of the ski.

The manufacturer I'd say would supply the point on the ski that is the location for the ski to bend such that it reaches its 'perfect arc' for carving.

Then you want to ski the dang thing and take some real time data that shows where you are putting the most pressure -- relative to that point.

Then slide the bindings about to match them up.

OR -- you can change your technique to move the point too...

I mean something has to be static here -- so someone came up with the idea of using the "ball of the foot" as the ideal pressure point on the human foot -- and then it becomes an issue of learning this technique, and moving the ball of the foot over this magic pressure point on the ski...

well what if you don't like the ball of the foot, maybe you ski just fine, expert even and yet somehow don't feel its really the ball of the foot.

well that's not really the issue, I mean the ball of the foot is just someone's ideal -- and for you it would be to find that "pressure point" relative to you -- and then move it over ski's ideal pressure point.

ANd all this just to make a perty turn in the snow -- hogwash really, but something to think about i guess
comprex
November 6, 2007
Member since 04/11/2003 🔗
1,326 posts
I am not sure I understand all of the previous post, but, KevR, it sounds as though you're trying to work towards the idea of

Greatest range of available movements starting from the skier's best natural balance point.

which is a little bit different than the idea of

Most efficient movements starting from the skier's best natural balance point.
Denis - DCSki Supporter
November 6, 2007
Member since 07/12/2004 🔗
2,220 posts
 Originally Posted By: comprex
Denis, it doesn't.

It finds which part of your foot,

( when placed in a ski boot, ramped forward with foodbeds and miscellaneous wedging gizmos shoved under it)

is to be mounted on the center of running surface.



Thanks Comprex. That makes perfect sense. I must have asked a dozen people this question in the past and I don't think any of them understood this.
KevR
November 6, 2007
Member since 01/27/2004 🔗
786 posts
Not really -- all I was getting at is it would be better to have dynamic model based on real data measured while skiing vs what to me is a rather static model based on the ball-of-foot & related measurement system.
comprex
November 6, 2007
Member since 04/11/2003 🔗
1,326 posts


Ah. Okeydoke.

That's a valid thought, but, IMO, really not feasible on amateur resources.

Hard to avoid getting bogged down by
too much data
too slow, too weak analysis tools
too many divergent optimisation goals.
KevR
November 7, 2007
Member since 01/27/2004 🔗
786 posts
There's no way to take such measurements that I'm aware of ...

I'm agreeing with you -- you said you doubted the validity of the ball-of-foot model in not so many words.

I agree -- it's just a model someone cooked up -- its a static model that probably has some benefits but may not in reality be something to strive for exactly for many.

Instead its probably more important to feel like you are skiing how you'd like to ski...

However if you want to move the binding around a bit, experiment -- by all means; try it -- try measuring "over" the "ball-of-foot" if you want and use that as a guide for binding placement.

I just think it would be better to measure the dynamic loads while skiing against some ideal -- which is impossible, so there you are ... stuck with the ball-of-foot idea.

Which reminds me, I've never understood how ski manufacturers measure the turn radius of their skis. Is there some industry standard incline, snow depth, speed, and load applied? Or what?
comprex
November 7, 2007
Member since 04/11/2003 🔗
1,326 posts
 Originally Posted By: KevR
There's no way to take such measurements that I'm aware of ...


There is indeed a way to do it, and people doing it:
http://www.tekscan.com/medical.html

http://aolsvc.timeforkids.kol.aol.com/skinet/travel/article/0,26908,364980,00.html
http://www.wipo.int/pctdb/en/wo.jsp?wo=2005116951

 Quote:

I'm agreeing with you -- you said you doubted the validity of the ball-of-foot model in not so many words.


Nah, I just think there is SO much more going on than easily described that a perfectly valid model isn't really useful at the moment to hackers like us, without years of research data.

Search over on epic for ground reaction force to see what I mean.

 Quote:

Which reminds me, I've never understood how ski manufacturers measure the turn radius of their skis. Is there some industry standard incline, snow depth, speed, and load applied? Or what?


Good question. ;\)
KevR
November 11, 2007
Member since 01/27/2004 🔗
786 posts
Wow -- cool! That is what you need - but you then need to tie that data to the dang ski bending data and terrain data, so you can figure if the perfect arc was achieved... perhaps some snow data would be necessary as well, not sure.

(I guess... )

And if not, appropriate adjustments made.

Which I think is largely irrelevent to most but theoritically interesting ... sort of.
comprex
November 11, 2007
Member since 04/11/2003 🔗
1,326 posts
 Originally Posted By: KevR
Wow -- cool! That is what you need - but you then need to tie that data to the dang ski bending data and terrain data, so you can figure if the perfect arc was achieved... perhaps some snow data would be necessary as well, not sure.

(I guess... )


Read the second article to the end.

My favorite quote:

 Quote:
After reviewing the data from all three sessions, Joanne turned to me and said flat-out, "At this point, I would recommend lessons." My ego fought to recover from the blow. How could she know that the problem was in my technique? Sophie explained that if I had a physiological problem, she might see little to no pressure in the ball of the foot. In that case, Sophie would build orthotics to restore functionality. In my case, however, technique was at fault.


Be sure to catch the 'skiing myths' part.
KevR
November 12, 2007
Member since 01/27/2004 🔗
786 posts
In the end it doesn't matter of course. Take this person down a tree filled slope in 2 ft of powder and they'll fall apart ... so in some sense I think there's an overemphasis on this one factor of skiing (carving) -- as skier ranking.

BUT having said that -- if someone would define the ideal by which one can aspire in terms of carving, then the data could be collected to see how close one is getting to it ...

That seems interesting to me, although useless to many.
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