by Bun-chan » Sat May 19, 2018 1:17 pm
Fascinating discussions.
I remember seeing some still pictures of WC slalom racers with their ski tip up as they go through gates. I was surprised and thought they do in fact ski in the back seat. But, they still looked in balance and fine, so I even thought perhaps there should be a backseat moment at the end of the turn. But I still was not sure if that was the case probably because I didn't believe PMTS advocated any back-seat skiing technique.
But, when I happened to find Harold's Saturday, January 14, 2017 blog some time ago, I was so excited because he addressed the very topic that I had been wondering about. Thank you Harold!
It is interesting to know that the movement is done "unconsciously" and occurs as a result of "efficient" skiing. After reading HH's blog, I was able to have a fresh look at those images and realized that, while each skier's newly released ski tip is up, his/her newly weighted ski is in contact with snow with its tip down. That, I think, means those skiers are not in the back seat.
Now, I wonder if I could get some feedback for my observations (two viewpoints) of the skip tip lifting -- from anyone, especially PMTS experts -- given the fact that the movement is unconsciously done as a result of efficient skiing. The following views are my observations, analyses and interpretations of the movement:
1) Friction from snow
As a weighted ski travels on snow, there exists a frictional force between the ski base and the snow surface. In other words, there is a force working against ski moving forward no matter how good your ski wax is. So, at the moment the ski is unweighted (lifted) at the release, the frictional force suddenly disappear. That causes the ski to travel faster than it has been traveling until the releasing moment. In the meantime, your foot, leg and body still pretty much maintain the same speed before the release. So, right after the release, the ski move forward slightly faster than other body parts. That, I think, causes the ski tip to rise slightly. Apparently those things happen in a split second.
2) Counter acting movement
I also think counter acting movement of the upper and the lower body may contribute to the ski tip lift. If you have been pulling back your inside/free foot and keeping strong counter balancing movement until the moment of release, at the moment of release, I don't think your old (recently unweighted) stance ski's tip should be pointing downward. If it is pointing downward, I suspect that would mean that you are not doing enough counter balancing or that you are prematurely unwinding your lower body from your upper body.
Any thought, link to other articles/videos, etc. would be appreciated.