An Aerodynamic Study of Bicycle Wheel Performance Using CFD

Abstract

A methodology is presented to apply CFD to study air flow around a rotating bicycle wheel in contact with the ground. The bicycle wheel studied here is an accurate geometrical representation of a commercial racing wheel (Zipp 404). Reynolds-Averaged Navier Stokes (RANS) and Delayed Detached Eddy Simulation (DDES) results are computed at a range of speeds and yaw angles commonly encountered by cyclists. Drag and side (or lift) forces are resolved and compare favorably to experimental results obtained from wind tunnel tests. Vertical forces acting on a rotating bicycle wheel are presented for the first time. A unique transition from downward to upward acting force is observed as the yaw angle is increased. Flow structures are identified and compared for different yaw angles. It is expected that a more complete comprehension of these results will lead to improvements in the performance and handling characteristics of bicycle racing wheels used by professional cyclists and triathletes.