Way too many good thoughts and questions to answer at length - I stopped halfway through
You can bend your ankles left and right, laterally. This movement tips the boots/skis onto their edges.
Inversion and eversion are whole foot movements, not just in the ankle.
This is perhaps my favorite photo:
You can clearly see how the flexed leg allows foot tipping and how the tipping on the inside foot is driven from the bottom up, i.e. from inside the boot, given the relative position of the cuff! You'd never leave the ankles behind, to be dragged around by the knees... would you?
You can also see how the boots are matched (i.e. the inside is held back).
I have found that when I consciously "close the ankle" in conjunction with pulling the feet back and engaging my turn forces, things work out better.
I don't really tip my ankles; I think of my skis as my feet and tip them when I ski.
When we pull the feet back, is the ankle closing due to action, or reaction?
I don't know the answer, I'm asking.
Closing the ankle, dorsiflexion, like most other movements, should not be a passive movement. I.e. the ankle is not passive when closed by say pulling the heels back, they work together. The TA muscle (Tibialis Anterior) tends to be very well developed in racers and good skiers.
My ankles tend to stay closed purposefully, for some of the turn. And my TAs tend to be much bigger at the end of the season
I don't race so I can't speak for why all (or any) racers would use that method. Maybe it's universally easier if you're racing (i.e. fast speeds, arcing hard turns, and on groomed hard-snow terrain) to use that method.
All I was saying is there are different cues that different people use to get themselves forward and flex their ankles...at least in the recreational world.
As you flex to let the skis surface up in powder, or on bumps, it is critical to maintain ankles closed and pullback the heels, even if only to not let the tips of the skis drop and get out of control. If you have any kind of room inside the boot, where you should have some, you will need to be proactive to control the tips as you flex, especially on soft snow or bumps where you unweight a lot.
You can also flex the ankles by moving the hips forward.
pliny the elder
Not really, I don't think. How do you move the hips forward? Forward of what? It's in fact the complete opposite. To "push" the hips forward, is rather impossible if you don't keep the heels back at the same time, and you will then likely use the toes to push, i.e. pedal motion, i.e. the opposite of closing the ankles.
Remember the hips have a lot of mass and inertia, in fact we are much more free to move all the extremities in relation to the core rather than the other way around!
As you begin to extend the inside leg in preparation for the edge change, you focus on making the femur more vertical and moving the hips ahead of the feet.
COM moves diagonally across the skis into the new turn.
pliny the elder
No... First off, the inside leg rarely extends. Depending on the performance, of course, but it tends to stay around 90 degrees or so for expert recreational skiing, extending slightly if at all.
Also, "more" vertical femurs means standing up in transition - it's relegated to a subset of transitions... not the most performant ones. You can also see closed ankles above. He's not on the backs of the cuffs.
Also, extending
before the transition will always push the COM
back and up the hill, not forward across the skis. Think about the geometry before transition (left above). The only way to let the COM flow across the skis is to relax and flex the outside leg... the opposite of "extension".
my 2c,
cheers