The effect of velodrome geometry on determining cyclists CdA: an explorative study

Abstract

Aerodynamics are an important factor in competitive cycling and easy and realistic aerodynamic measurement methods are helpful for the riders and coaches. An indoor velodrome, minimizing the environmental effects, could be a suitable location for quick, reliable, and easy measurements on cyclist CdA. However, the effect of banked straights and bends on the CdA determination remains unclear. The goal of this study is to investigate how the track geometry impacts the CdA measurements. Two methods for the calculation of CdA where compared, one that does and one that does not take track characteristics into account. For the measured CdA, no difference between the two methods was found. Additionally, a moderate intraclass correlation was found between the two methods and the drag measured in a wind tunnel (method 1: ICC = 0.76, method 2: ICC = 0.77). A difference in drag of 7.6 Watts and more at a speed of 50 km/h was found to be accurately measured by both methods. In the bends, a significantly lower power output was found, resulting in a different CdA value between the bends and straights. This difference remains after taking the track characteristics into account. It can be concluded that for velodrome aerodynamic drag measurements, the banking and bends do not have to be considered. In this study, no conclusion can be drawn on the found differences in CdA between the bends and the straights. Future research could determine whether these differences are due to incomplete dynamics or a real difference in aerodynamics.