With the advent of shape skis the custom footbed serves another purpose. It provides a flat platform for the skier to stand on. This minimizes the effects of pronation (flat arch-knock-kneed) or supination (high arch bow-legged). This allows the skier to ride a flat ski and engage the ski's edge effectively by rolling the feet and knees. This sets the stage for the skier to be more precise with turn initiation and controlling the shape of the turn.