The current ASTM ski binding setting standard, Practice for Selection of Release Torque Values for Alpine Ski Bindings (F 939-93), was evaluated by comparing the forces measured during alpine skiing to the ASTM recommended release forces. For a twelve subject sample, the forces and moments at the toe and heel ski release bindings were collected during skiing, walking, and executing stationary turns. The subjects included all skiing levels from beginner to professional racers and varied widely in weight and age. For each subject, the maximum lateral force at the toe and vertical force at the heel was measured during runs where falls and releases of the binding did not occur.
The ASTM recommended release settings were significantly higher than the forces required to ski normally for ten of the twelve skiers. For nine of the subjects, the vertical force at the heel required to ski (retention setting) was less than 45% of the vertical release force permitted by the standards; these subjects could have reduced their release setting at the heel by 55% (between 425 and 711 N) without causing inadvertent releases of the binding during the skiing maneuvers. Similarly, ten of the subjects skied within 67% of the current settings and could have lowered the lateral release setting at the toe by 33% (from 61 to 111 N) without signaling for inadvertent release; for inexperienced, lightweight skiers, the release setting at the toe could have been lowered by 38%.
A method for determining the minimum retention forces required to ski in these tests for any and all force components at the toe and heel binding is presented. These minimum retentions do not correlate well (r < 0.7) to subject to age, height, or weight. Furthermore, weight was found to be a poor predictor of the maximum lateral force at the toe and vertical force at the heel. Accordingly, setting standards cannot rely primarily on these variables for prediction of minimum retention.