Development and Validation of an Apparatus for Determining Snowboard Boot Stiffness

An apparatus for measuring the mechanical properties of snowboard boot/binding systems in bending was designed and constructed. The apparatus was designed so that the direction of loading could be specified for a full 360° about the tibial axis of a prosthetic lower limb. Moment about the ankle joint was measured as a function of ankle rotation. Testing was conducted on two different boot/binding systems to evaluate device sensitivity. Two ankle joint configurations (articulating and rigid) and several boot strap tightness levels were also evaluated. Bending stiffness was calculated as the slope of the moment-rotation curve. Stiffness values were found to be a function of loading direction, boot/binding type, and surrogate leg and ankle design. Stiffness values varied with loading direction (e.g., forward lean, backward lean, medial bending, and lateral bending), ranging from 0.64 Nm/deg to 3.02 Nm/deg for the articulating ankle joint and with values as high as 10.38 Nm/deg for the rigid ankle in backward lean. Testing standards have not yet been developed for snowboard boot and binding designs, nor are there standardized methods for determining the physical properties of boots and bindings. The type of apparatus designed in this experiment can be used to quantify mechanical properties of the boot/binding system. These data may be useful in developing standardized tests and in better understanding the performance of these systems in the field.