Computational Fluid Dynamics Study of the Effect of Leg Position on Cyclist Aerodynamic Drag

Martin D. Griffith, Timothy Crouch, Mark C. Thompson, David Burton, John Sheridan, Nicholas A.T. Brown

Research output: Contribution to journalArticlepeer-review

44 Citations (Scopus)


An experimental and numerical analysis of cycling aerodynamics is presented. The cyclist is modeled experimentally by a mannequin at static crank angle; numerically, the cyclist is modeled using a computer aided design (CAD) reproduction of the geometry. Wind tunnel observation of the flow reveals a large variation of drag force and associated downstream flow structure with crank angle; at a crank angle of 15 deg, where the two thighs of the rider are aligned, a minimum in drag is observed. At a crank angle of 75 deg, where one leg is at full extension and the other is raised close to the torso, a maximum in drag is observed. Simulation of the flow using computational fluid dynamics (CFD) reproduces the observed variation of drag with crank angle, but underpredicts the experimental drag measurements by approximately 15%, probably at least partially due to simplification of the geometry of the cyclist and bicycle. Inspection of the wake flow for the two sets of results reveals a good match in the downstream flow structure. Numerical simulation also reveals the transient nature of the entire flow field in greater detail. In particular, it shows how the flow separates from the body of the cyclist, which can be related to changes in the overall drag.

Original languageEnglish
Article numberFE-13-1381
Pages (from-to)1-9
Number of pages9
JournalJournal of Fluids Engineering, Transactions of the ASME
Issue number10
Publication statusPublished - Oct 2014
Externally publishedYes


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