A Comparative Aerodynamic Study of Commercial Bicycle Wheels Using CFD

Abstract

A CFD methodology is used to study the performance of several commercial bicycle wheels over a range of speeds and yaw angles. The wheels studied in this work include the Rolf Sestriere, HED H3 TriSpoke, the Zipp 404, 808 and 1080 deep rim wheels and the Zipp Sub9 disc wheel. Wheels are modeled at speeds of 20mph and 30mph, in contact with the ground, using Reynolds-Averaged Navier Stokes (RANS). Drag, vertical and side (or lift) forces are reported for each wheel. Turning moments are also calculated using the resolved side forces to examine aspects of stability and maneuverability. Drag and side forces over the range of yaw angles studied compare favorably to experimental wind tunnel results. The previously reported unique transition from downward to upward acting vertical force on the Zipp 404 wheel for increasing yaw angles is observed for all deep rim wheels and the disc wheel studied here. Wheels were also modeled at a critical yaw angle of 10 degrees using Delayed Detached Eddy Simulation (DDES) to examine the transient aspects of flows around moving bicycle wheels. It is hoped that a more complete comprehension of these results will lead to improvements in performance, safety and control of bicycle racing wheels used by amateur and professional cyclists and triathletes.