A phase-averaged analysis of the pedalling cyclist wake

For a posture and pedalling frequency representative of an elitelevel time-trialist, wind tunnel experiments show, perhaps for the first time, the changes to the wake flow topology over the course of a dynamic pedal stroke. Velocity field measurements are made in the wake of a full-size pedalling (100 RPM) mannequin in a time-trial position sitting on a bicycle. Using a phase-averaged approach, the wake structures passing through a downstream measurement plane are analysed as a function of crank cycle and are compared with similar wake measurements taken for static leg positions at fixed crank angles. It is found that the same fundamental fluid mechanisms that lead to the formation of the large-scale flow structure variants and wake asymmetries are consistent for both quasi-steady and dynamic pedalling conditions.