High-resolution friction measurements of cross-country ski bases on snow

Participants in the sport of snow skiing devote considerable effort to reduce sliding friction of the ski. A large industry is devoted to providing products and ski preparation methods with claims of improved ski performance, sometimes at considerable expense. Despite this attention to the topic, there are very little data available to skiers that quantify the effect these products and methods have on reducing ski friction. Determining the coefficient of friction of a ski on snow presents a significant technical challenge. Our approach has been to develop a tribometer incorporating a series of proximity sensors to test commercially available ski equipment and waxes on natural snow. We developed a test protocol that significantly reduces the experimental noise associated with variable environmental conditions enabling us to differentiate the difference in friction between two pairs of skis with a resolution of 0.001. A large body of test data was acquired over a wide range of environmental conditions to quantify the effect of ski wax and base texturing treatments in terms of coefficient of friction in a way that is of practical use to skiers. An exercise physiology power model was used to estimate the ski race time difference that could be expected from changing the coefficient of friction.