Per - I see a lot of this kind of knee drive on roller skis with my skiers compared to how they ski on snow. I think that a lot of it has to do with the weight of the roller skis and, even more importantly, the rolling friction of the roller ski compared to a ski on snow. When the roller ski lands it slows down much faster than a ski would causing the foot to fall behind the knee during the glide phase. This causes a chain reaction right up through the body with it being harder for the hips to rise over the foot and the back to arch. Have you measured this friction vs snow friction to see if this is actually the case?
Hello Jack! Quit busy times so I haven't had the chance to respond to your comments! The equipment is an issue, of course. Anyway, the feedback was given to the athlete, and he was able to correct the technique more according to his skiing technique :-) The pendulum of the foot after the kick was done together with the rise of the body on the gliding foot and he was able to move the hip higher above the gliding foot and the kick was much better timed, and thereby much more similar to his skiing technique on snow at the left video! We haven't measured the friction and compared that to the roller resistance, however, our roller ski track is normally done 3-5 min faster on roller skis than on skis at competition speed. So, this is important and must be considered when comparing ski and roller ski. Ski reg Per-Øyvind
Congratulations again for the effectiveness of these videos...merci
Thanks Per, I'll have to have a Norwegian friend translate for me.
Yes and I think the Colors on the Lines (red and green) hjelps to understand the feedback given to the skier !
Per - I see a lot of this kind of knee drive on roller skis with my skiers compared to how they ski on snow. I think that a lot of it has to do with the weight of the roller skis and, even more importantly, the rolling friction of the roller ski compared to a ski on snow. When the roller ski lands it slows down much faster than a ski would causing the foot to fall behind the knee during the glide phase. This causes a chain reaction right up through the body with it being harder for the hips to rise over the foot and the back to arch. Have you measured this friction vs snow friction to see if this is actually the case?
The length of rollerskis and the ratchet giving s perfect kick may also be issues.
Hello Jack! Quit busy times so I haven't had the chance to respond to your comments! The equipment is an issue, of course. Anyway, the feedback was given to the athlete, and he was able to correct the technique more according to his skiing technique :-) The pendulum of the foot after the kick was done together with the rise of the body on the gliding foot and he was able to move the hip higher above the gliding foot and the kick was much better timed, and thereby much more similar to his skiing technique on snow at the left video! We haven't measured the friction and compared that to the roller resistance, however, our roller ski track is normally done 3-5 min faster on roller skis than on skis at competition speed. So, this is important and must be considered when comparing ski and roller ski.
Ski reg Per-Øyvind