Impact of wheel rotation on the aerodynamic drag of a time trial cyclist

Abstract

Aerodynamic drag is the main resistive force in cycling at high speeds and on flat terrain. In wind tunnel tests or computational fluid dynamics simulations, the aerodynamic drag of cycling wheels is often investigated isolated from the rest of the bicycle, and sometimes in static rather than rotating conditions. It is not yet clear how these testing and simulating conditions influence the wheel aerodynamic performance and how the inclusion of wheel rotation influences the overall measured or computed cyclist drag. This study presents computational fluid dynamics simulations, validated with wind tunnel tests, that indicate that an isolated static spoked front wheel has a 2.2% larger drag area than the same wheel when rotating, and that a non-isolated static spoked front wheel has a 7.1% larger drag area than its rotating counterpart. However, rotating wheels are also subjected to the rotational moment, which increases the total power required to rotate and translate the wheel compared to static conditions where only translation is considered. The interaction with the bicycle frame and forks lowers the drag area of the front wheel by 8.8% for static and by 12.9% for the rotating condition, compared to the drag area of the isolated wheels. A different flow behavior is also found for static versus rotating wheels: large low-pressure regions develop from the hub for rotating wheels, together with a lower streamwise velocity region inside the circumference of the wheel compared to static wheels. The results are intended to help in the selection of testing/simulating methodologies for cycling spoked wheels.

The Performance-Result Gap in Mixed-Reality Cycling – Evidence From the Virtual Tour de France 2020 on Zwift

“…Van Erp and Sanders, (2020) show that in professional cycling races maximum mean power over shorter durations (<5 min) are higher for riders who are placed in the top-10 of a race than for riders who are not in the top-10. In addition to physiological parameters, factors such as the bike mass and body mass (both are particularly important in the mountains; Jeukendrup and Martin, 2001) as well as aerodynamic components such as body position, bike frame, and wheels can affect the competition result (Faria et al, 2005;Malizia et al, 2021). Based on their machine learning approach, Kholkine et al (2020) assume that factors such as weather, team strategy, road conditions, or mechanical failure must be included when predicting a competition result.…”

A low-cost, open-source centrifuge adaptor for separating large volume clinical blood samples

“…As an example, the radial distance of design B-45˚is 0.931 mm higher than that of B-30d esign and the RCF value is 16×g lower. This effect can be explained by the aerodynamic drag force acting during the rotation which is directly related to the drag coefficient (depends on the shape of the body), the frontal area and the square of the rotating velocity [36]. The frontal area of design A and B can be compared to a flat plate that is highly resistive to the surrounding air and have a high drag coefficient of 1.17 to 1.98 [37,38].…”

Impact of Disc Wheel Geometry on Aerodynamic Performance: A Computational Fluid Dynamics Investigation

“…In addition, the rotational moment coefficient C M (Eq. 4) is included in the present study due to its importance for the wheel performance [19,35,36]…”

“…A front wheel is selected for the investigation of the impact of wheel geometry in this paper because front wheels have a greater contribution to the total drag and the flow over a front wheel is less disturbed by the bicycle and the cyclist [36]. First, three-disk wheels with flat side plates are investigated.…”