Abstract: Skis are manufactured so as to have a convex longitudinal curvature in the unloaded state. This ensures that the ski has good contact with the snow, keeps to the track and does not chatter during skiing, but impedes turning the skis and skiing through narrow curves. However, by securing two Z-shaped rigid levers (10) with a power arm (11) and a load arm (12) to a ski (1) such that the power arms (11) are positioned under the heel or toe of a ski boot and by variously distributing the weight (Gh, Gv) on the power arms (11), the tail (3) and/or tip (2) of the ski are/is lifted and the ski (1) obtains a concave longitudinal curvature.