While everyone recognizes the importance of good balance in the dynamic environment of skiing I have yet to find an explanation of what good balance is, let alone a description of the conditions under which a skier is in balance during actual ski maneuvers. In order to talk about balance, one needs to be able to describe all the forces acting on the skier, especially the opposing forces acting between the soles of the feet of the skier and the snow surface (ergo – applied and ground or snow reaction forces). Without knowing the forces involved, any discussion of balance is pure conjecture. In 1991, I formulated a hypothetical model that described these forces. A biomedical engineer and I designed a device to measure the 3-dimensional forces applied by the foot and leg of the skier to the internal surfaces of the boot during actual ski maneuvers. Test subjects ranged from Olympic and World Cup champions to novice skiers. By selectively introducing constraints that interfered with balance responses we could reduce an expert skier to the level of a struggling beginner or set up conditions that would enable a novice to use balance processes similar to those of Olympic champions. To the best of my knowledge, no one had ever done a study of this nature before and no one has ever done a similar study since. When analyzed, the data captured using the device calls into question just about everything that is accepted as fact in skiing. This study was never published. For the first time I will present the data and describe the implications in future posts. We called the device shown in the photo the Birdcage. It was fully instrumented with 17 sensors strategically placed on a 3 dimensional grid. Be prepared to be surprised.