Originally Posted by Bud
Well, I don't know if our interpretations are the same? If the objective is to extend like a tree grows on the uphill edge and interrupt a smooth crossover, then yes I agree. But why and in what situation is this productive? Granted it is how many skiers ski (even many level III's, unfortunately) but that doesn't make it efficient? does it?... Sure a diverging step turn where we delay the edge change to gain a higher line may be the objective may be palatable. If the intent is to change the rythme of the turn shape and delay the crossover...O.K. I can see that. Certainly, even in this task there is a limit, if the edge change to the BTE does not occur before the leg extension is complete from the uphill ski there would be an interruption in a smooth crossover.
Bud, here's my view.
There are multiple concepts of efficiency. Balance efficiency,,,, efficiency of muscular involvement,,,, structural efficiency,,,, edge application efficiency,,,, CM path of travel efficiency. It's seldom possible to achieve maximum efficiency levels simultaneously in all areas. Often we must sacrifice ultimate efficiency to achieve a specific objective, and the particular need/desire for each turn dictates which efficiency area we must override.
As an example, lets look at balance. The most efficient state of balance is through the foot balance, with no leg leveraging against the boot upper. Here, pressure is distributed across the heel, big ball, and small ball,,, and the body weight causes the trusses of the foot to compress and provide a natural balance platform. It also provides the best opportunity for skeletal alignment, and the least muscular supplementation.
But we sometimes want to move our point of balance away from fore/aft neutral. Such as when we move our CM forward to intensify the arc at the top of the turn, or move back at the end of a turn to speed the exit. Both efficiency sacrifices to achieve a specific objective.
How about structural efficiency? The more countered we get the more our structural strength suffers. But staying square does not always provide for efficient balance. So here we must make a choice; one efficiency area must be granted priority. And knee angulation? Big structural weakness, but sometimes we need to use it.
And how about the efficiency area you mentioned; the path of the CM down the slope. Just as you suggest, any uphill movement of the CM constitutes a disruption of the CM flow. You provided a very good example of a legitimate purpose for degrading that efficiency. Stepping at the end of the turn requires an uphill movement of the CM, but it provides a bit of speed generation, or an end of the turn radius reduction that may be deemed worthy of the sacrifice.
Your second example was good too. During long, sweeping turns we don't want to quickly dive into a new high edge angle. Rather, we want to roll off the old edge and into the new turn slowly, and apply higher degrees of edge gradually. Efficiency dictates we just transfer pressure and let the external forces of the turn do the work for us, but we can slow down the natural transition process by moving our balance point and CM slightly uphill before the pressure transfer.
|I don't know? Can you give me an example of where we can "efficiently" make a turn transition without the CoM moving inside the new turn (inside edge engaged on new outside ski) before any extension is complete or a change in support foot (more than 50% bias) has occurred. I just can not visualize efficiency in the same turn as a vertical (like a tree grows) extension? Am I missing something?
I think you may be envisioning a more radical extension occurring during ILE than actually happens. It takes very little extension of the inside leg to create a pressure transfer from the old outside to old inside foot. Once the pressure transfer has taken place the extension remains very subtle, creating a constant state of pressure on the old inside ski until the edge roll over has occurred, and the new turn forces start to emerge and reestablish balance. The tree doesn't reach maturity until later in the new turn.
I think, from what you write here, that you envision a big tall extension on the uphill edge of the old inside ski. It's not the case. It's just a first move difference (ILE vs OLR) that achieves the same thing, pressure transfer. The advantage is in the superior feel for turn initiation and edge development ILE provides. The sacrifice is a bit more muscle involvement.