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The Importance of Femur Rotation in Carving

razie

Sir Shiftsalot
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What I see there is this: skier balanced on the outside ski, which is engaged strongly. The ski is bending and turning, never going "straight". You can keep this static posture until you're turned 180 and pointing uphill and falling backwards...

What do you want to do: turn with the ski or separate? If I want to separate, I relax in specific areas and allow the femur to rotate with the ski (yes, femur rotation is a 3D movement when you consider the simultaneous adduction and abduction) or counteract with the body - that's a different discussion, but both are premised on the separation at the hip.

What do you want to do: keep the ski turning or release the ski? If I want to release, I relax the long leg and allow the edge to disengage - the long leg flexes in the process. I've jammed enough bottoms of enough turns to know that the leg can stay long and not release the ski even with a lot of femur rotation, until you decouple the ski's edge from the body.

I still remember this specific one - guess which frame is "UGH" with a lot of femur rotated and no flexing:

jam-bottom.png


The difference between left and right is more relaxation, with allowed more flexing which allowed more adduction, with roughly the same degree of femur rotation.

All these happen normally at pretty much the same time and you want to be as little "on the power" as possible - that is perhaps the big and only secret that there is... not to mention that many discussions completely ignore adduction and abduction, without which we should not even have a discussion of a turn and without which femur rotation is useless.

All of these movements (rotation, adduction, abduction, flex) can be passive or active. Above I described a passive approach, based on relaxation, which is effective, efficient and how I want to ski most of the time, unless I'm out for a quick workout. However, if the timing of this or that turn is not perfect, some active input is needed here and there, as a compensation... but I think even here, adduction and abduction have a bigger role to play for compensations when you use flexing.

cheers
 
Last edited:

Uke

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Loki1 is making a fundamental error that has been made by many others. He is using a static two dimensional representation (a picture) of a dynamic activity that takes place in four dimensions to to try to explain what's happening. As F Pugh explained flexion or extension of either leg immediately affects the trajectory of the com and it is the altered path of the com that moves the body from one side of the skis to the other or possibly further away from the outside ski to tighten the arc.

One more point. Gravity only acts in one direction, straight toward the center of the earth. So gravity has no role in moving the body lateraly across the skis that's all due to momentum. Hence, I don"t topple into a new arc I fly, glide or sometimes vault into the new arc.

uke

P.S, Some femur rotation is necessary to effectively engage/balance on the new edges but it isn't necessary to move from one side of the skis to the other.
 
Last edited:

James

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In this image if the skier extends and only extends his right(inside) hip, knee, and ankle; his whole body would move in the direction of the arrow. Resulting in the inside leg taking over pressure and balance and no changing of edges.
07CA52D8-D1C9-489C-8EDE-EE9EA98BCA47.jpeg


That’s the same as being still uphill and trying to flex or extend yourself into edge change. Won’t happen so people jump, twist, push off the downhill ski.

Again, if your body is too far uphill, you can flex to your ear and you still won’t release/go downhill. Just like if your body is too far up the stairs, you can’t go down the stairs when you flex the leg. You’ll just get shorter and or fall back.

In the one legged skiing, Bode is also steering the one ski with his leg. There’s one shot where it’s quite clear.
Plus he’s doing 50mph.

Wooden soldier turns have almost no femur rotation. There’s probably a little. The legs are pretty straight, there isn’t any knee angulation.
You could do them a lot better by allowing the inside leg to get shorter. If you stay square to the skis there’s little abduction or adduction of the femur. So practically, no rotation.
 

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