The wind-averaged aerodynamic drag of competitive time trial cycling helmets

This paper documents a wind tunnel test program that measured the aerodynamic drag (Fd), lift (Fl) and side force (Fs) of 12 contemporary time trial (TT) helmets at yaw angles of 0 to 15∘. Fd measurements at yaw were subjected to a novel analysis technique adapted from the automotive fuel efficiency literature to provide a single wind averaged drag at a velocity (v) of 14.75 m sec−1 (53 km/h). Ranked wind averaged Fd measurements of TT helmets provide a simple performance index and it is recommended that this analytical procedure be adopted by the bike industry to permit uniform Fd comparisons of helmets, wheels, frames and other components that are subjected to yaw angle wind tunnel tests.