Just a few comments on tdk6's post:"CoM is high at transition and low at apex. CoM is moving like a sinus curve up and down. This is caused by a vaulting effect of standing tall with extended legs at transition and inclination and angulation close to the snow at apex. Pressure is reduced when CoM is dropping and pressure is increasing as CoM is rising. Pressure is also increased as centrifugal force kick in and comes to a max when CoM is going up and the centrifugal force starts pulling in the same direction as gravity after apex. Cuch and Grandi plays with these forces and even jump up in the air during transition."
The highest pressure on the skis is just before or at the apex. It is caused by the centripetal/centrifugal force. The shape of a good turn traced on the snow is close to a sinusoid (not a radius of a circle). At the apex the instantanious radius is small, so the centripetal/centrifugal force is maximum. Look at the edge angles Grandi is getting:
More than 60degrees to the snow!!. At 60degrees the centrifugal force is 2X gravity, and the force/weight acting on the COM is 2.2X the weight of the skier. If this wasn't the case, Grandi would fall over to the inside. What I am trying to say here is that in these dynamic racer turns, the force on the COM at the apex is mostly centrifugal.
So the opposite of what you say above - the pressure INCREASES as the COM drops."No rotation of femures in hip sockets. Maybe Grandi and Quay just a hint and they do it with their outside leg. End up in A-frame a bit. No anticipation to mention. They use upper body counter very moderately and therefore they do not end up anticipated."
Look at the photo above. The skis are going somewhat across the hill, and the body (including the hips) are going more down the hill - countered body. The only way to make this happen is through femur rotation on the hip socket. The ankle cannot rotate because it is clamped into the boot. The knee is mostly a hinge joint, and cannot rotate. Try standing with your leg slightly flexed, and hold you femur. Now tip your foot as if to edge a ski - you should feel your femur rotate some."They are not flexing and extending. Only flexing and extending their inside leg but the outside leg is extended all the time. They do not have to worrie about gates so they just carve round arcs as dictated by speed, ski turn radius and stiffness, snow consistence, inclination and edge angle etc."
Look at Grandi, as he goes by in the transition:
He has some ankle flex going on. He is also not standing up tall (straight legs). In the previous picture his inside knee is almost up into his chest, and his boot is directly under him. Try doing that without serious ankle flex. His outside leg is almost straight - no ankle flex. I would suggest that there is a lot of flexion and extension happening.
Flexion and extension need not happen to both legs simultaniously.
Look at the comments by simplyfast on the 'Sudden down push at apex - valid technique or not' thread. Most of these guys in the video extract are not skiing their best.