Characteristics of antifriction devices used for ski bindings.

These tests suggest that various antifriction devices do reduce the amount of torsion that can be transmitted to the skier's tibia during a slow twisting fall. It was shown that under various environmental conditions the antifriction devices are effective. Dirt negatively affected the performance of some devices. The importance of protecting bindings and antifriction devices from contamination cannot be overemphasized. It was shown that some antifriction devices perform better than others. In most instances the performance of the plate type of binding compares favorable with that of toe-heel bindings using antifriction devices. For the plate type of binding the dirt particularly had a detrimental effect. It should also be pointed out that these tests were run with one particular binding. These results would not necessarily be the same if the tests were conducted with another binding system. For instance, the limited motion of some of the antifriction devices (Lotork, Skidder) may impede their performance when used with bindings requiring a greater travel distance before release. The performance with other boot soles may be different from that with the particular boot sole used for these tests. Performance might be improved with a harder, smoother boot sole. Similarly, the effectiveness of the antifriction device may be reduced by the use of boot soles with a coarse pattern or relatively soft treads. In this test series a relatively small number of antifriction devices were evaluated. One should not presume that all devices will perform with equal effectiveness. Another factor, equally important, is the correction for the height of antifriction devices. Antifriction devices raise the boot sole from the ski surface, and if this change in height is not accounted for, the boot sole may effectively interfere with the operation of the toe or the heel unit. In summary, it can be stated that when properly applied and selected, antifriction devices make a significant contribution to skiing safety.