Interesting to see what happens when you ask a pretty open question. I had in mind more concrete information that is measureable than feelings. I suppose if you measured everything you might be able to get at the feeling part.
Right now what do we have for info on racers? Total time and split times -just time, that's it.
In Ron Lemaster's [ www.ronlemaster.com
] slide show he does a graph for starts of various racers. He's plotting angle of the poles versus time. I'm not sure what this tells us but this is more along the lines of I was thinking about. Specific data: force, angle, speed, position in space, that one could use to compare the turns of different racers. For two reasons, one is to just to learn and compare turns, the other would be to make it more interesting to watch.
I guess one of the easiest, most direct things to measure would be maximum g-force in the turn. This could even be reported like split times are now. "Herman was pulling 2.5 g's in that last turn there." Though just because one pulls a lot of g's doesn't mean they were faster in the turn?
I suppose the basic thing to have would be the "line" that the racer takes. For this we would want a 3 dimensional computer topo map of the selected turn. Then we could plot the turn on that, but which part of the body would define the line? The middle of the boot sole? We certainly would want to know where both feet are at each moment-this would tell us stance width over time.
It's been suggested to know how the racer initiates the turn. I suppose even before that we'd want to know the speed before initiation and what's happening in terms of the skier's momentum. Are they "drifting" or skidding in a direction other than optimal and need to correct?- What would tell us that in terms of data?
Ok. we've got the line the boots are taking so we could map the edge angle and see where the turn is initiated. Also how the skis are pointing to tell the initial steering angle for the turn.
So we'd want to know where the feet are and where the skis are. I suppose for the skis if you plotted points from the tip,tail, middle and maybe a couple others you could get the position of the skis and their flex.
Then there's the forces. Force on the bottom of the foot, force on the boot tongue, (I guess you might as well record it front,back and sides of the cuff to get a good picture). I suppose if you know the forces and the edge angle you could tell the transfer point to the next turn? (Then there's the issue of how to determine edge angle? You'd want to know in relation to the surface I suppose)
The video analysis software sounds very interesting. It's sort of what I was thinking of - if you could make the image a stick figure and record all the different angles. Better than video I think would be if you could record the absolute position of the points on the body. If we knew the position of the critical points we're interested in and the time we could use that to show how they're moving. This would be like the video but maybe more accurate since it's based on their absolute position in space instead of what's seen from one point of view.
I suppose this is becoming picturing the turn in 3 dimesions. If you can picture how the body moves and correlate it with the forces on the skis and velocity (which would also tell you acceleration) then you could start making comparisons on initiation, transfer etc.
This is getting complicated, I need a break. Maybe back to an earlier question. If you're watching a race on tv, what would it be interesting to know?
Also, has anyone seen this device e-coach which tells you when you're pressing on the boot tongue or back? Think it's worthwhile? http://www.vist.it/html/uk/produkte.htm
Ed, certainly come back and give us your thoughts.
[This message has been edited by Tog (edited June 13, 2001).]</FONT>