Hi Mosh, and welcome to EpicSki!
And hello everyone! I've been out of touch up in northern Maine for a couple weeks now. I see you've all been busy....
When does a turn begin? There are several "correct" answers to this question--it's more philosophical than technical, isn't it? I like Ott's answer--it begins when I choose to change direction. Traditionally, that would be the "preparation phase," when I prepare both mentally and physically for the direction change. I may look in the new direction, choosing my path and looking for traffic, and I may turn parts of my body--arms, head, and torso--slightly in the new direction, stretching and strengthening the muscles that may be involved in beginning the direction change of the skis. Other preparatory movements may also take place--the pole swing begins in the preparation phase.
But there is no new direction change in the preparation phase. In linked turns, these activities clearly take place at the end of the previous turn, not the beginning of the new turn. If we define the essence of turns--as I do--as changes in the direction of motion of the center of mass, then a new turn would begin at the moment the curve transitions from left to right, or vice-versa. If a turn represents an arc--part of a circle (more or less}--then the turn begins the moment the "inside" of the circle changes sides. I can't agree with you, Rick, that a turn has nothing to do with the center of mass. It has everything to do with the center of mass!
This moment of transition coincides, in contemporary skiing, with the moment of "neutral." "Neutral" suggests that the skier is neither leaning left nor right, the skis are flat on the snow as they roll from one set of edges to another, the weight is equal on both skis as it flows from old outside ski to new outside ski, and the skis are pointed straight ahead, neither turned left nor right. Neutral is a fleeting moment of no duration whatsoever. It is NOT a "position" that we move to and from. It is more like a doorway that we pass through without stopping. A car passes through neutral also, when cruising through an S-turn, as the driver turns the wheels from left to right in a smooth, continuous movement. Like the skier, the weight is equal left to right at that moment, but it flows quickly toward the new outside wheels.
So the physical and mental process of making a direction change begins before the direction change actually begins (which is traditionally known as the beginning of the "initiation phase"). Either the preparation phase or the initiation phase could properly be argued the "beginning" of the turn.
One thing that is important, though, is that in modern skiing the motion from turn to turn and throughout each turn is usually continuous, flowing, cyclical. There really is no distinct beginning or end. You could argue for any point in the cycle being the transition from one turn to another.
Interesting things sometimes happen to skiers when they consider a turn to begin and end "in the fall line" (the moment the skis point directly downhill), and that the s-shaped path between these points represents one turn. This thought can often help smooth the transition through "neutral," resulting in a breakthrough to the next level of smoothness! If I'm reading Ydnar correctly, this is the point he's describing. Until the fall line, you are moving either left or right across the slope. After the fall line, you are moving the other direction.
Anyway, good question, Mosh! As for me, since Loveland is apparently open in Colorado, my own turns should begin in just a few days!
Edit--I see Roto also suggests the fall line as a good place to think of the starting and ending a turn. I'm glad to see that it's a popular, if a bit unusual, idea!
<FONT COLOR="#800080" SIZE="1">[ October 22, 2001 06:35 AM: Message edited 1 time, by Bob Barnes/Colorado ]</font>