[quote]Originally posted by Rusty Guy:
A movement of the cm to the inside happens as a result of a turn depending upon speed, pitch, etc. It is not something that we actively do. It is a component of the right movements enhancing balance.
I agree with you that movement of CM has a hormonic relationship with edge angle, speed, pitch, etc. The question here is what starts the chain of events. Do we wait for forces to grow to move the CM inside to oppose them, or do we move the CM inside to create them?
Think of it this way: Our main objective is to turn the ski in a new direction. We know to do this we have to put the ski on edge and apply pressure to engage the sidecut, so the question becomes what bio mechanism will we use to put the ski on edge.
To answer this we should focus on two absolutes:
1) An aligned, straight leg is much stronger for resisting turning forces than an angulated, flexed leg.
2) The outside leg is where the majority of the forces of the turn should be directed because it is bio mechanically best suited to resist those forces. (we can discuss this at greater length if anyone desires)
In consideration of those two truths I would think we would all agree that it would be most efficient to maintain a stright/alligned outside leg for as much of the turn as possible. To keep the leg in such position the hip and knee must move in synchronism with the tipping of the foot.
If we tip the foot first and leave the hip static we put the leg in a knee angulated position which leaves it structurally weakened. In this situation the forces are not being directed through the hip and into the foot, but are attempting to drive the CM over the top of the feet and muscular supplementation must be employed to assist in the battle to avoid that happening. This puts big time stress on the knee.
Even if we allow the hip to move inside the feet once we feel the forces grow we are for a moment in a structurally weak position until we can make the necessary structural adjustment, and as the turn develops and more edge is applied we continue to play catch up to the feet with the CM if we continue to apply this strategy. This is probably an advisable approach for someone who is just learning to balance the forces of a turn, but as we become more refined in our ability to balance these forces we should strive for synchronization of hip/knee/foot, and be able to employ that synch very rapidly to a high edge. This is the key to efficiency in carving.
On the subject of parallel tib/fibs. Once a student is doing some sort of christie or matching, barring horrible alignment issues, I would constend shafts line up fairly naturally whether skidding, scarving, or carving.
Perhaps. Remember though that each of those type of turns with similar radius will create different forces, and therefor will require a different position of CM to achieve optimum balance.
Remember the days of straight skis? We saw body positions with CM more over the feet then we do with shapes. This is because those skis did not create the forces the new skis do so CM was not required to move inside as much, if fact it damn near impossible to get way inside with CM without our butts ending up on the snow. This more upright position was the origin of the pyramid knees we remember, we angulated the outside knee and kept the inside foot flat to discourage the hip from falling in so we could remain in balance. This was the predominant slalom technique where slow speeds made the use of hip very hazardous.
That same situation occurs on shape skis when making steered turns at slow speeds. The hip must be kept more over the feet to facilitate good balance on the outside ski because the forces are so low. Pyramid knees are therefore not necessarily a mistake in this situation. As the turns gravitate towards carves the forces will grow and with them the need to bring the hip more inside which will naturally pull the inside knee along with it producing the parallel lower legs we associate with modern technique.
I'd love to hear you expound on your idea a little more. Are you suggesting for one student we would teach certain movements and for a second student a different set? Are you suggesting we present all the "ways to skin the cat" to every student and allow them to ferret out what is best in their case?
Same set of skills to all students, if that is possible within the parameters of your teaching environment. Yes, that would include all skinning methods, introduced in an order of easy to more difficult, accompanied by an explanation of possible applications for each why we might choose a particular one in a particular situation. A normal base rule of thumb is that edge release from the new outside ski after weight transfer is for most students easier than release from the new inside ski before weight transfer so I would suggest starting a student with that technique, though I know that may be painful for some ears to hear. Understand that disengagement of an edge can only be done from a pressured ski, if there is no weight on the ski there is nothing to disengage. Therefore disengagement of the new inside ski edge is basically a white pass lean move which is a more advanced balance task and I would logically think a technique for later introduction.
There is also retraction unweighting for pelvis reconfiguration, tail pressure retraction for pelvis reconfiguration with rapid leg extension, extension of outside leg turn completion, inside leg extension with pivot, and retraction with pivot as additional turn transition techniques, but lets save something for another day.