Aerodynamics of a cycling wheel in crosswind by coaxial volumetric velocimetry

Abstract

The aerodynamic characteristics of a modern road cycling wheel in crosswind are studied through force measurements and 3D velocimetry in TU Delft’s Open Jet Facility. The performance of the 62 mm deep rim is evaluated for two tire profiles, and yaw angles up to 20^◦ . All measurements are executed at 12.5 m/s (45 km/h) freestream- and wheel-rotational velocity. The wheel’s rim-tire section in crosswind is found to behave similar to an airfoil at incidence, ultimately resulting in a reduction of the wheel’s aerodynamic resistance with increasing yaw angle magnitude. This trend, also referred to as the sail-effect, is limited by the stall angle of the tire-rim profile. The stall angle is found to be dependent on the tire surface texture and varies between 14^◦ and 20^◦.