Aerodynamic characterization of bicycle wheels: Development of a reversed-fork setup for drag and ventilation moment measurement

Aerodynamic resistance plays a fundamental role in cycling races. Since competition time gaps are continuously narrowing, aerodynamic optimization of technical equipment has gained crucial relevance. Therefore, wheel aerodynamics has been extensively investigated through wind tunnel experiments and numerical simulations. Although it has been demonstrated that ventilation moment accounts for a significant portion of wheel power losses, it is not measured in most wind tunnel tests concerning bicycle wheels. This paper aims to introduce and validate a setup in which the bicycle wheel is supported by a reversed fork, enabling the simultaneous measurement of rotational power losses and aerodynamic forces. The presence of the fork can produce a more realistic flow field, potentially offering insights into the frame-wheel interaction. The proposed methodology combines a coast-down test and an inertia measurement to estimate the rotational power loss due to ventilation moment with maximum uncertainty of about 1%. The outcomes of the tests agree with the results reported in the literature, indicating that the flow behavior is accurately captured. Comparison with previous wind tunnel campaigns conducted within the same facility, but with a different setup on the same wheel-tire assembly, revealed consistent trends of translational drag force and steering moment with yaw angle.