Descending

Abstract

Professional cyclists show a big difference in descending abilities. Eventhough recently research has been conducted on the control of a bicycle [13,19], little is known about the techniques of descending in cycling [[3,6,22]. The aim of this study was to develop measurement equipment which can measure skill and perfor- mance in cycling during descents. The final goal was to measure differences between slow and fast descenders. On the basis of a literatur study [8], the important variables for descending were identified. The measure- ments equipment must be able to measure these important variables; roll angle, steer angle, rear and front brake force, location and forward speed of the bicycle. The roll angle was measured with infrared distance sensors, the steer angle using a string potentiometer and the brake forces with a aluminium tube instrumented with strain gauges. A high performance GPS was used to determine the location and speed of the bicycle and a mathematical model was used to translate the location of the bicycle into path coordinates of the track. Furthermore, a third-person video camera was mounted behind and above the participant to get a overall impression of the ride. An observation study with 6 professional cyclists has been performed. The professional cyclists rode each time the same descent track located at La Plagne, France. The track had a length of 1.0 km and a descent height of 67 m. Both the cyclists and their individual bicycles were instrumented with the measurement equipment. Each cyclist completed a minimum of 4 trials. The cyclists were instructed to go as fast as possible down the track, but they were confined to their own lane and not allowed to pedal. The mean time was 77.68 s and the fastest and slowest time were respectively 75.97 s and 80.32 s. The results show that the best indicator for the fastest descent time is the braking technique. A fast time seems to be highly correlated with a late braking point and a high braking force. Differences in the positions on the road were expected to influence the descent time, but unfortunately these differences fell within the measurement inaccuracy. Future research should be mainly focussed on improving the measurement equipment.