|In the first series the subject(Bob ) seems to be in the center of his skis. With no upper body rotation involved as he follow his skis . In the lower pictures the seam on the coat seems to be entering the turn previous to the skis path. I'm not sure this is truth or illusion. My point is when we teach young people ,say a 6-7 year old when we ask them to turn their feet to define the path of a gliding wedge they will nearly always match with their upper body the suggested path they are telling their feet to go. This bilateral movement would also reinforce and implant a non desired rotary movement right from our first instruction of a gliding wedge turn.
Wouldn't it be better to have both skis on edge and then ask them to roll a knee into the hill thereby flattenning the inside ski and the pressure and direction of the outside ski would generate the turn. The inside ski would naturally enter into a christy without much ,if any ,coaching. It seems this would reinforce edging and pressure as turn tools and not put such a demand on the use of rotation that might get abused or used incorrectly through new habits.
My experience with this is drawn from a clinic by an Alpine Team member demonstrating a proper gliding wedge turn and christy.
This seems to be one place where introduction of rotary movement presents a slippery slope that can take students in a direction they would be better served not to go .
Is this a misinterpretation on my part or something that should be handled very carefully as a stepping stone and not a means to a parallel turn in that the rotary aspect seems to be enforced intead of diminished ?
Regarding the relationship of the upper and lower body, I suggest that this simple-sounding concept actually needs some clarification. What, exactly, is the "upper body," and where is the separation (pivot point, stretch zone, whatever) between "it" and the "lower body"? It's actually the main differentiation between "leg rotation" and the upper-body-based rotary mechanisms (rotation, counter-rotation, and blocking pole plants). In leg rotation, the pelvis is part of the upper body, and pivot point(s) are the hip sockets. In the other mechanisms, the entire lower body works as a unit against the upper body, with the hips moving typically more as part of the lower body and the pivot point (or zone) generally in the abdomen and lower spine.
Keep this thought in mind as you look at these illustrations, which show primarily leg rotation. (Note that one clear sign of leg rotation is that lines across the ski tips and across any two sides of the body--knees, hips, shoulders, hands, etc.--remain parallel. This relationship is clearly shown by the parallel lines across ski tips and hands in the basic turns illustrations. In this respect, with leg rotation, "tip lead" equates to "counter.") The legs rotate independently of each other in the hip sockets beneath the pelvis, very similar to the steering movements of the front wheels of a car as they pivot in the wheel wells beneath the chassis.
So, at the moment the turn begins--I call this the "neutral point," the moment the edge(s) release allowing the new arc to begin--the skier remains still somewhat countered (facing downhill) from the previous turn. This gives the illusion that the skier has rotated the upper body into the new turn. In fact, though, the legs and skis are rotating beneath the pelvis (and upper body) as I described. This "steering" activity (whether active--muscular--or passive is irrelevant to this discussion) began way back in the previous turn, resulting in the counter of the upper body decreasing--but not disappearing--by the neutral point. It continues through that point and into the new turn, causing the skis and body to become "square" and then developing new counter as the turn progresses.
In other words, what matters is not the position at any moment--countered, square, rotated--but the movement that is happening at that moment. We can counter-rotate from a rotated position, for example, just as we can steer our feet (or allow them to turn, if you prefer) from a rotated position. And that is what is happening in these turns. The turn begins from a slightly rotated position with respect to the new turn (still countered from the old turn), but the legs are turning beneath the pelvis, in a movement that will eventually result in a new countered position (upper body facing toward the outside of the turn) in the new turn.
The point that may be of contention remains the question of exactly where and when the skier becomes "square," or the equivalent--where and when does the lead change from one ski to the other. I contend that it is generally ("by default") after the turn begins, as I have shown in these illustrations. This not intended to be a directive either--it is an effect of sound movements, and should not become a goal or an end in itself. I don't advise trying to assume any particular position at the transition--situations will cause variations--but it is very important at least to give yourself permission to move in these ways.
Now to your second point ("Wouldn't it be better to have both skis on edge and then ask them to roll a knee into the hill thereby flattenning the inside ski and the pressure and direction of the outside ski would generate the turn")--also a great point! My answer is "yes," although I'm tempted to inquire, "better than what"? You have described movements I would advocate teaching as fundamentals of basic turns at any level. And as an exercise, it's a fine focus to play with at some point in a beginner lesson.
However, (there's always one of those, isn't there?) as you have described it, you will make a turn whose shape is dictated by your ski, not necessarily by you. That's fine, until you need to make a smaller turn than your skis can carve, especially likely with the limited edging skills and minimal pressure (force) involved in most beginners' turns. What if your skis aren't taking you where you want to go? As you wrote, the "direction" of the ski is part of the equation, and the rotary skill is nothing more than how you control that!
So, to make that smaller-than-your-skis-can-carve turn, you will need to actively steer your skis, in addition to (not instead of) the tipping and pressuring movements you've described. It's this active (muscular) rotary input that makes wedge christies tend to happen at low speeds and skill levels. They're not a goal, and the turns are certainly not "wedge-based." No one says you "have" to make turns smaller than your skis can carve, but the ability to do so when needed is, I would argue, critical! Certainly, there is plenty of time in most beginner lessons to explore the effects of pure edging and pressuring movements, to "ride the arc" of tipped skis, and so on--and I suspect that most good instructors play with these movements a lot, when appropriate. They're just not all there is to it. Adding accurate rotary movements to the mix and blending all the movements together surely is more difficult than just "tipping and ripping." But real control, versatility, and expertise demand it--and taking shortcuts to "easy" is not always a sign of a great instructor!
In conclusion, it is important to note that good ski instruction--as advocated by all national instructor organizations that I'm familiar with worldwide--emphasizes teaching a balanced blend of skills and movements, whatever is needed to get the job done (whatever "the job" may be). It would be a specific violation of good teaching principles to over-emphasize, or to ignore, any particular skill. Rotary, as I've said before, is not a directive. But it is an essential skill!