I just want to say, if anyone has to make a big forward move through transition, then pure and simple, its a "corrective" move and indicative of errors leading up to it. So no, should not need to make a big forward move, nor should we have to teach anyone to make a big corrective forward move. If someone is too far aft approaching and through transition, then go further back in time to find the issue.
Well said, BornToSki683 (post #29)--we should not need any effort to create the "X-Move," unless we've made some error prior to the transition phase (that is, in the shaping phase). In a perfect transition, everything that has to move is already in motion, so all we need to do is let their momentum continue, without effort, until the next shaping phase begins. That's one of the defining differences between the way great skiers ski and the way most skiers ski. Most skiers make their biggest physical movements and muscular efforts as they initiate their turns, then move very little through the "shaping" phase as they brace against skidding, braking edges. Great skiers move constantly throughout their turns, managing pressure and edge angle and guiding skis through the shaping phase, and then end their turn--and begin the next--with a release of effort. Effort is required to resist the forces of the shaping/carving phase, but the transition is an opportunity to relax. As you say, if you can't relax in the transition, you should look back in time to find the error(s) in the shaping phase. I should add that the only real effort needed is to guide the skis (the direction they point) through this unweighted phase, when they obviously cannot carve, so that they point the direction you want them to point when pressure and edge engagement are re-established in the new turn.
We ski in a state of dynamic balance and this is a complicated subject for sure, but an overall statement I think I can make that we can all agree is that we have to MOVE WITH the skis in order to prevent getting into the back seat and this should be happening all the way through the turn, not just as a big corrective forward move while crossing over.
Also well said, BTS. My only concern here is the way words like these can be (and often are) misinterpreted. You are careful to imply that you do not mean this, but many will translate your words into the need to "move forward along the skis" in the transition. I hear this advice all the time, from instructors at all levels and incessantly from race coaches (a great many of whom appear at Loveland and A-Basin this time of the year, with teams from all over the country and international).
This misinterpretation of the need to "move forward at initiation" is the heart and soul of the issue, in my opinion. As the X-Move animation shows, and very apparent in the Hirscher and Medicine Ball videos, from my frame of reference my feet move forward of me in the transition--at least, if "forward" is defined as the direction the skis point ("moving with the skis"). As I (my CM) move forward down the hill I must allow my feet and skis to move forward in the direction they're going and get ahead of me in that direction. The result is often an apparent "back-seat" position for a moment in the transition when observed from above (uphill of) or below the skier. It looks "back." But it is not. (At least, when performed correctly.)
You (BTS683) mentioned the term "dynamic balance," which is a good way to put it. I call it "balancing in the fourth dimension." We commonly speak of balance movements in the three physical dimensions of fore-aft, lateral, and "up-down" (all from the frame of reference of the skier). Dynamic balance describes movements I make "now" in order to create balance "later." Balancing through time (the fourth dimension). Quite often, in high-speed turns especially, there is very little pressure on the skis during the transition--the skier may even become airborne. If we describe balance as the relationship between the center of mass and the base of support (that is, between the body and the feet), then balance becomes a moot point when there actually is no base of support. Can you be out of balance in the air? Freestylers usually answer this question with a "yes," but when I ask them how they'd know, they usually say, "when you land." In other words, the movements they make when they're in the air will only matter, with respect to balance, later in time, when they land.
And so it is with turn transitions. By definition, the transition is the phase between pressure/carving/shaping phases. It can be very brief or very extended. But either way, my primary job during this phase is to get into the optimal "position" or attitude such that I'll be balance when the new shaping phase begins. That's the moment the "catcher" catches the medicine ball in my animation. Prior to that, his "job" is to get into the perfect place to make the catch (which is, of course, "ahead of" the ball). If you follow the analogy, then, it is the "job" of my skis during the transition to move to the perfect place, relative to my Center of Mass, to make the "catch" and begin to carve in perfect balance. What does that look like? At the beginning of the shaping phase, my body (cm) must be "ahead of" (downhill from ) my feet, and my feet must be off to my side, toward the outside of the turn, to create the ideal angle of inclination (leaning) for balance. So the critical movements I make during the transition provide balance and ski performance later. Balance in the Fourth Dimension!
If anyone is following this line of thinking, it can lead to some fascinating, perhaps even paradoxical, conclusions. How do I "get forward" in a transition? By moving laterally (down the hill, which is off to my side when I am traveling across the hill). And how do I get inclined, with my skis out to the side and tipped on edge? I move "back" during the transition (relative to my feet)! In other words, fore-aft balance relies on accurate lateral movements, and edging/tipping relies on accurate fore-aft movements. A paradox? Only if you don't understand that I'm going a different direction when I make these movements that I will be going when they begin to serve their purpose. But only if you understand this apparent paradox does the "backseat moment" in Hirscher's (and many others) transitions begin to make sense as a correct movement, and not an error.
It may become clearer, or easier to grasp, if we eliminate the problem of "forward" changing direction every time I do. If we were to think of "forward" as "down the hill" and lateral as "across the hill," always, regardless of which direction I'm going, the analysis may become simpler. In the transition, I need to move forward of my feet--down the hill, while my feet need need to move away to the side--across the hill. That's pretty simple--and very true! And it allows us to think of that "backseat-looking" moment for what it really is--the phase when the feet are moving toward the outside of the upcoming turn. The following animation may help illustrate my point:
In this animation, the arrow pointing left illustrates "down the hill," while the two-headed arrow illustrates "across the hill." In the transition, my body needs to move down the hill (from my feet), while my feet must move across the hill--toward the outside of the new turn. Of course, when I'm traveling across the hill, "down the hill" is a lateral movement, and "across the hill" is in front of me! If I move accurately in the transition, I'll "land" at the beginning of the new pressure phase in perfect balance, carving on a clean edge. If I fail to move accurately in the transition, I'll need to make corrections in the pressure phase, actively pulling my body forward and/or twisting or pushing my skis off to the side--with the result that my turn, at least until I make the adjustments, will not be as clean and fast as it could be.
Notice in the animation how little effort is involved during the transition. When you get this right, it really is a feeling of floating, flying, gliding, and effortlessness, with the subsequent edge engagement clean and seamless, right from the start. The only thing I have to "do" (ideally) is guide the direction my skis point when they're not carving, so that they're pointing the right direction when I "land" on them. In other words, an accurate transition is critical to establish fore-aft and lateral balance and edge angle, but the only "active" (muscular, intentional) movements I need to make involve the "rotary" skill. The inclination and fore-aft movements will take care of themselves, simply as a result of the crossing paths and momentum of my feet and body. (Again, of course, this is the ideal. In most "real" turns, I do need to make corrective adjustments, for any number of reasons--sometimes subtle, sometimes vigorous.)