Pierre eh! & Rick H -
First, let me make sure I understand exactly what you guys are discussing. If I can paraphrase it down to a couple of sentences, I think the main argument is that:
(a) Rick thinks you can more quickly adjust your body position to stay in balance from a narrow stance, whereas,
(b) Pierre eh! thinks you can more quickly adjust weight distribution between the feet, (as well as body position) to stay in balance from a wide stance.
I think that the main reason for the disagreement is that (a) and (b) involve two different mechanisms to maintain balance. The bottom line is that I have to agree with Pierre eh! that maintaining balance from a wide stance is almost certainly quicker and more certain, but it will involve more energy expenditure.
For the purpose of this argument, lets consider a skier perfectly in balance, in the middle of a constant radius turn going at constant speed.
Case (a): In the limit of a very narrow stance, skiing on one foot, or even a snowboarder, the person must have adjusted his body position so that the combination of gravity and centrifugal force (pushing on him via his edge) goes exactly through his center of mass. If this isn't true, the person would start falling to either the inside or the outside of the turn and would need to correct this.
About the only thing any single-planker or narrow-stancer can do to smoothly get back in balance is to change the radius of his turn. He can do by changing his edge angle or by making changes in fore-aft pressure. As Pierre eh! essentially pointed out, such changes can be made with relatively little effort, but take a while for them to take effect.
Case (b): In a wide stance, the skier that needs to make a balance correction has another option open to him. He can immediately start pressing down with the appropriate leg. Even without making any change whatsoever in the position of the CM, this can get the person back into balance - its exactly what you do when you are standing still on the flats.
Now, after you do this, the weight distribution between your legs will certainly be altered from what you prefer (for example, you may want the outside leg to be carrying 80% of the weight on hardpack), but this is something that can be dealt with separately from the immediate issue of namely instantaneous balance.
For example, if the skier is starting to fall to the inside of the turn, he can almost instantly weight the inside leg more and immediately restore his balance. If he then wants to make sure his outside ski continues to carry the majority of the load, he can then push with his inside leg and raise his CM back to where it needs to be to get the desired L/R weight distribution. Unfortunately, actually moving your CM around like this takes energy, and hence this type of balance correction move, altho fast, will likely tire a person out more quickly than the edge angle (or fore-aft pressure) changes of case (a).
The bottom line is that both for theoretical reasons, and from my own (much lower level) sking experience, I have to agree fully with Pierre eh! and his concise explanation.
[This message has been edited by PhysicsMan (edited July 23, 2001).]</FONT>