Translational and rotational aerodynamic drag of composite construction bicycle wheels

Drag and side force measurements were made in a wind tunnel on disc wheels, deep-rim wire-spoked wheels, and ‘aero’ spoke wheels, which have three to five aerodynamically shaped compression spokes. The wheels were run at 30–50 kph and yaw angles from zero up to 50° yaw, covering the range of crosswinds usually experienced in outdoor races. Unlike previous studies, translational and rotational aerodynamic power losses are measured and reported separately. The disc wheels have the lowest power losses, but the ‘aero’ spoke wheels require little more power than the discs; the wire-spoke wheels require the most power. The best wire-spoke wheels experience less side force in crosswind than the aero wheels, although the best aero wheel tested approaches the side force performance of one of the wire-spoke wheels. Side force correlates with side projected area. Rotational drag affects the total drag significantly, and the choice of wheel should not be based on translational drag alone.