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# Rotation and carving - Page 2

Good question Tdk6.

Let's look closely at the interaction between the "edge" and the snow.

First let's look at Ideal carving on near-ice with a ski of a given sidecut on a flat hard surface. Only the metal knife edge contacts the icy surface, and approximating it as an edge is not too bad as a means of simplifying. The ski must be bent to particular curve for any given tipping angle. The tipping angle dictates what size curve can be carved in an ideal fashion. For example with a 30-meter-side-cut ski, tipping it to 70 degrees would result in the ski needing to be decambered into a 10 meter radius curve for the entire edge to touch the surface. Any displacement of the edge along the snow other than along it's length is clearly not carving a pure arc. Tdk is quite correct; the ideal pure carve is not happening in this zipper-line bump skiing.

Now let's look at what happens if there is sufficient give to the surface that the metal edge can dig in; a huge grove forms and thus the pushing "edge" becomes a large portion of the base of the ski, much more of a plane than an edge (the metal edge is really a very thin plane anyway). The top of this "edge" which is now really a quite wide plane, is the snow surface or maybe even the upper metal edge of the ski. The bottom of this "edge" is the metal edge. Think 3-dimensionally, the base of the ski (acting as a fat edge) directs the ski along it's direction, but the metal edges of the ski besides being bent into a small radius in the decambering direction, also curve in a different direction, the bottom metal edge curving into the snow. To truly follow along the direction of the metal edge, the skier would have to turn into the mountain and bury himself, but the ski can still follow the "fat edge" consisting of base and both metal edges.

What is happening here is the ski tips are being bent farther than the curve that would align the base-as-an-edge with the side-cut-prescribed shape of the metal edge for the giving tipping angle. The skier is "carving" on with the base. but it's not ideal pure arc, because the edges of that base are being dragged along with some slippage, just like they are when you run straight with a flat ski.
When I "skid" the skis move in a direction that is neither tangential to the metal edge on the bottom side edge of the ski, nor tangential the "base-as-an-edge".
Ghost, that's a really cool distinction. I never really thought about the difference between the arc described by a decambered ski and the arc described by the decambered ski's edge. I think I learned something important from that post. All kind of ideas are racing through my head. Wow
:: Now that we have been infiltrated by the semantics artists, all normal conversation is lost...

Michael
Quote:
 Originally Posted by barrettscv :: Now that we have been infiltrated by the semantics artists, all normal conversation is lost... Michael
Still not clear on whether you were talking about upper body (counter-)rotation, or lower body (leg) rotation or steering (scarving, skidding, drifting, brush) in your first post.
Quote:
 Originally Posted by telerod15 Still not clear on whether you were talking about upper body (counter-)rotation, or lower body (leg) rotation or steering (scarving, skidding, drifting, brush) in your first post.
Generally I'm talking about upper body, the kind presented in the photo.

As a secondary point, I'm not convinced that all lower body rotation results in a skidded turn. (I think) I've used lower body rotation to tighten the line without skidding. Its not always possible to hold the edge and apply lower body rotation, its only effective when the edge is secure and gear & conditions permit.

I'm also mudding the waters by saying that bumps, powder and steep natural (ungroomed) slopes often require both forms of rotation. Rotation is needed to tighten the line and may produce a carved turn or a good quality skidded turn.

I don't find rotation to be the problem, maybe its just the excess use of ineffective rotation that must be managed?

Michael
Barret,
If your skis are describing arcs and your knees are bent, you lower body has to rotate. Indeed lower body rotation that matches the skis rotation is essential to good carving imho. It's just torquing your skis about an axis perpendicular to the snow using your body as the driving force that's not helpful to carving.

Good upper/lower body separation and timely upper body counter rotation is all good and does not hinder carving in any way.
Quote:
 Originally Posted by barrettscv Generally I'm talking about upper body, the kind presented in the photo. As a secondary point, I'm not convinced that all lower body rotation results in a skidded turn. (I think) I've used lower body rotation to tighten the line without skidding. Its not always possible to hold the edge and apply lower body rotation, its only effective when the edge is secure and gear & conditions permit. I'm also mudding the waters by saying that bumps, powder and steep natural (ungroomed) slopes often require both forms of rotation. Rotation is needed to tighten the line and may produce a carved turn or a good quality skidded turn. I don't find rotation to be the problem, maybe its just the excess use of ineffective rotation that must be managed? Michael
Thanks for the clarification. I agree with every point you made here.
Quote:
 Originally Posted by Finndog I think you are more accurately describing body countering, where it's very helpful to have your body traveling in the direction opposite of the skis. This is another one of those areas of symantics and subleties. There is nothing wrong (in my book) with doing that in all aspects of skiing. In this picture, your skis are heading to the right (skiers left) and your body is heading to the left following your pole plant. I am assuming you are intending on the next turn to go to the left. This is a good thing. Just release you edges, let the skis run flat as they turn towards the left to follow your body, re-apply the edges together and finish the turn.
Hi Ron,

Yes, that's what is intended and the result.

Cheers,

Michael
Quote:
 Originally Posted by Ghost Good question Tdk6. Let's look closely at the interaction between the "edge" and the snow. First let's look at Ideal carving on near-ice with a ski of a given sidecut on a flat hard surface. Only the metal knife edge contacts the icy surface, and approximating it as an edge is not too bad as a means of simplifying. The ski must be bent to particular curve for any given tipping angle. The tipping angle dictates what size curve can be carved in an ideal fashion. For example with a 30-meter-side-cut ski, tipping it to 70 degrees would result in the ski needing to be decambered into a 10 meter radius curve for the entire edge to touch the surface. Any displacement of the edge along the snow other than along it's length is clearly not carving a pure arc. Tdk is quite correct; the ideal pure carve is not happening in this zipper-line bump skiing. Now let's look at what happens if there is sufficient give to the surface that the metal edge can dig in; a huge grove forms and thus the pushing "edge" becomes a large portion of the base of the ski, much more of a plane than an edge (the metal edge is really a very thin plane anyway). The top of this "edge" which is now really a quite wide plane, is the snow surface or maybe even the upper metal edge of the ski. The bottom of this "edge" is the metal edge. Think 3-dimensionally, the base of the ski (acting as a fat edge) directs the ski along it's direction, but the metal edges of the ski besides being bent into a small radius in the decambering direction, also curve in a different direction, the bottom metal edge curving into the snow. To truly follow along the direction of the metal edge, the skier would have to turn into the mountain and bury himself, but the ski can still follow the "fat edge" consisting of base and both metal edges. What is happening here is the ski tips are being bent farther than the curve that would align the base-as-an-edge with the side-cut-prescribed shape of the metal edge for the giving tipping angle. The skier is "carving" on with the base. but it's not ideal pure arc, because the edges of that base are being dragged along with some slippage, just like they are when you run straight with a flat ski.
This is a very interesting post, Thanks, JR
Unless someone can show me how they ski without any aduction or abduction of the femur then all skiing uses a degree of rotation.

Even the 'railing' carve that this forum appears to be obsessed with involves simultaneous abduction and aduction of the femur, both to maintain edge angle and to release edges in the transition.

If there is no rotatry movement then you are just riding the edge and any intermediate punter can do that if he/she has enough speed and smooth terrain.
Andrew,

Quote:
 If there is no rotatry movement then you are just riding the edge and any intermediate punter can do that if he/she has enough speed and smooth terrain.
You are right. Too bad more skiers don't share your point of view.

RW
It is very easy to ride the edge, and alter the turn shape by changing the tipping angle. It is very sad that more intermediate skiers don't seem to be able to it.
Quote:
 Originally Posted by Andrew R If there is no rotatry movement then you are just riding the edge and any intermediate punter can do that if he/she has enough speed and smooth terrain.
Can you specifically define the rotary movements included above?
Quote:
 Originally Posted by Ghost It is very easy to ride the edge, and alter the turn shape by changing the tipping angle. It is very sad that more intermediate skiers don't seem to be able to it.
I agree. Tip more, flex the inside leg, and add in some counter acting movements and a skier should be able to bend the ski quite nicely.
Quote:
 Originally Posted by Max_501 I agree. Tip more, flex the inside leg, and add in some counter acting movements and a skier should be able to bend the ski quite nicely.
Its all relative to the conditions and terrain, in Michaels picture, there is little need to tip much nor to flex the inside leg much more than the outside leg. The two legs, in this scenario should work more as one following the terrain. More like 45/55% pressuring, edging is done to "feel", more flowing with the terrain. I don't know the exact words but it seems like the countering with the upper body drives the legs and subsequently the skis? On groomed stuff, yes, I would agree though.
Quote:
 Originally Posted by Max_501 I agree. Tip more, flex the inside leg, and add in some counter acting movements and a skier should be able to bend the ski quite nicely.
Max, I know "No rotation" is your baby, but I still don't understand what you believe allows you to "tip more" without rotating your femurs in their hip sockets. If I lean sideways against a wall with one thigh shortened and tip my feet laterally as in skiing, if I wish to increase that tipping, my femurs rotate (without moving my hips) and point in the direction of my shortened thigh. Don't yours?

If I deliberately force my shortened thigh to point straight up (i.e., not rotate to match the direction of my longer leg), it certainly doesn't feel very good!
Quote:
 Originally Posted by mike_m Max, I know "No rotation" is your baby, but I still don't understand what you believe allows you to "tip more" without rotating your femurs in their hip sockets. If I lean sideways against a wall with one thigh shortened and tip my feet laterally as in skiing, if I wish to increase that tipping, my femurs rotate (without moving my hips) and point in the direction of my shortened thigh. Don't yours?
When you ski do you intentionally block your hips so they can't fall into the turn? This has been gone over so many times its getting tiresome. When I tip my inside foot my hips move with the tipping. This is because I'm stacked (hip above the knee which is above the ankle, I keep them in a straight line) and co-contracted. Tipping the foot activates the kinetic chain which results in the hips moving farther into the turn.

If you lean against the wall then you block the hip movement so it doesn't work. Many of these little dryland test thrown around on Epic are not representative of what happens on snow.
Quote:
 Originally Posted by Finndog Its all relative to the conditions and terrain, in Michaels picture, there is little need to tip much nor to flex the inside leg much more than the outside leg.
I disagree. If you want to ski at a high level you'll need to learn to tip, tip, and tip more.
in those conditions? nahh. Don't agree. On the groomed I agree 100%. Not in this picture.
Max, I think you are misinterpreting my point (or perhaps I'm misunderstanding yours). When I say to keep my hips still, I am referring to not allowing the rotation you dislike to enter into my upper body, which can easily result in an unintended twisting of the skis and skidding of the tails. I can also turn my hips AWAY from the direction of the turn (more straight down the hill) to add the counter you and several others correctly advocate. This counter of the hips and connected upper body has the effect of tightening the turn radius. One can steer (don't you love that word!) where you want to go simply by how much you turn your hips AWAY from the direction of travel. The more hip counter, the tighter the turn; the less counter (following the direction of the tips), the longer the turn radius. The amount of counter does not have any effect on the independently rotating femurs which are physiologically necessary to increase the tipping in our feet. If you continue to keep your body square to your skis and let your hips follow the direction your skis are going (up the hill eventually) you simply traverse up the hill.
Quote:
 Originally Posted by Max_501 ...When I tip my inside foot my hips move with the tipping. This is because I'm stacked (hip above the knee which is above the ankle, I keep them in a straight line) and co-contracted. Tipping the foot activates the kinetic chain which results in the hips moving farther into the turn.
Max,

I actually agree with both the logic and practical application of this technique. If I understand you correctly, tipping (and angulation) reduces the need for rotation. Tipping promotes clean carve, while rotation can result in a skidded turn.

This is my general strategy on groomed runs. I would like to think that I can clean carve every turn, however the very-steep stuff at places like Snowbird require more input. Rotation can foreshorten the transition from turn to turn. Rotation can also tighten the line without skidding if the edge grip allows and the skier has the skill.

In bumps and powder there really is no controversy, rotation is needed to change direction.

Sincerely,

Michael
Michael, do you differentiate betwen Rotation and Countering or are we talking symantics to you? I think sometimes its one in the same, depending on the degree of input. A lot like intentional skidding vs, scarving vs. controlled skids, all the same to me. All are used to control turn radius and speed.
Quote:
 Originally Posted by Finndog Michael, do you differentiate betwen Rotation and Countering or are we talking symantics to you? I think sometimes its one in the same, depending on the degree of input. A lot like intentional skidding vs, scarving vs. controlled skids, all the same to me. All are used to control turn radius and speed.
Hi Ron,

I hope that in December while skiing with you and Gary we can figure this all out. Of course, it might require many, many runs and then a few beers to argue the fine points.

To me rotation is a simple concept. Any time the upper body twists on a vertical axis you have rotation. Countering should only be a more narrow definition or type of rotation. I assume you mean that countering is the kind of contra-rotation (against) that is seen in the picture at the beginning of the thread. Am I correct?

Michael
Quote:
 Originally Posted by barrettscv In bumps and powder there really is no controversy, rotation is needed to change direction.
Why do you say it is required in powder?
Quote:
 Originally Posted by ilh Why do you say it is required in powder?
Well... yes...that is what I said (I'm beginning to regret it )...

I could see using the reverse camber of the ski to establish turns without rotation. But in practice, this would work best performing GS turns. Most good powder skiers on steeper terrain I've observed are using rotation.

Michael
The preceding few posts illustrate one of the major difficulties we have here because of our differing concepts of the meanings of certain terms. For what it's worth, these are the meanings of some of these terms as I understand them and use them:

"Rotation" is an inefficient turn mechanism incorporating a fairly gross twist, usually of the upper body, in the desired direction of the new turn. It forces the skis to come around and change direction, but encourages skidding, setting of a platform preceding the turn, and tends to create an a-frame in the knees.

"Counterrotation," likewise, is an inefficient turn mechanism which is characterized by a sudden twist of the upper body and hips, working as one connected unit, opposite the direction of the ski tips and the new turn. This twists the skis sharply and is often seen in bump skiers who have their legs locked together and their arms out quite wide. This technique precludes actually guiding the skis in varied turn radiuses but can function as a falline bump technique as the skier slides straight down the hill with the skis rotating like windshield wipers.

"Counter" is a controlled and progressive turning of the hips and upper body opposite the direction of the ski tips to help adjust turn radius as desired (see posts 47 and 51 above).

"Independent femur rotation" or "Independent leg steering" is the movement of the femurs independent of the hips which allows both a direction change on a relatively flat ski, as well as an increase or decrease in the amount of tipping of the feet. This also allows controlled adjustment of turn radius (see post number 51 above).

I know these definitions are contrary to the understanding of some, but how can we discuss movements if what we are labeling them is not understood by all in similar terms?
Quote:
 Originally Posted by mike_m Independent leg steering; is the movement of the femurs independent of the hips which allows both a direction change on a relatively flat ski, as well as an increase or decrease in the amount of tipping of the feet.
In one case the feet rotate left or right. In the other they tip (invert or evert) without any left/right redirection. Given that the outcome is so different, why not limit the definition of femur steering/rotation so that it means the movement that results in the feet rotating left/right? Then use the word 'tipping' to describe tipping.
Quote:
 Originally Posted by Max_501 In one case the feet rotate left or right. In the other they tip (invert or evert) without any left/right redirection. Given that the outcome is so different, why not limit the definition of femur steering/rotation so that it means the movement that results in the feet rotating left/right? Then use the word 'tipping' to describe tipping.
This would make things much easier to understand and differentiate.
Nicely done Mike. Good definitions but I do agree that tipping should have its own definition here. I think the two are very different although I understand your point. I think to Max's point, the act of tipping does not require any active input from the femurs or hips.
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