Drag and Side Force Analysis on Bicycle Wheel–Tire Combinations

Abstract

Aerodynamic forces on bicycle racing wheels were investigated experimentally in a wind tunnel facility at the University of Calgary. The main geometric parameters investigated were the tire sidewall width, (21.40 mm≤T≤26.15 mm), rim depth, (55 mm≤D≤90 mm), rim width, (19.28 mm≤W≤25.75 mm), and angle of attack, (0deg≤ψ≤12.6deg). A total of six wheels and five tires were tested. Coefficient of drag area (CdA) and coefficient of side force area (CsA) versus angle of attack (ψ) were measured using a multi-axis force transducer. Wind tunnel conditions were set to simulate 2.94 m/s (6.6 mph) wind speeds and 13.4 m/s (30 mph) cyclist speeds. The performance of the wheel tire combinations was assessed using a wind-averaged drag method. The results show that the CdA of aerodynamic wheels is highly dependent on the wheel-tire combination. There is a strong linear correlation between wind averaged drag (CdA¯) and the ratio of the tire and rim width (T/W). The CsA of wheels is primarily controlled by the rim depth (D) and only weakly correlated with tire width (T).