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Aerodynamics has such a profound impact on cycling performance at the elite level that it has infiltrated almost every aspect of the sport from riding position and styles, equipment design and selection, race tactics and training regimes, governing rules and regulations to even the design of new velodromes. This paper presents a review of the aspects of aerodynamics that are critical to understanding flows around cyclists under racing conditions, and the methods used to evaluate and improve aerodynamic performance at the elite level. The fundamental flow physics of bluff body aerodynamics and the mechanisms by which the aerodynamic forces are imparted on cyclists are described. Both experimental and numerical techniques used to investigate cycling aerodynamic performance and the constraints on implementing aerodynamic saving measures at the elite level are also discussed. The review reveals that the nature of cycling flow fields are complex and multi-faceted as a result of the highly three-dimensional and variable geometry of the human form, the unsteady racing environment flow field, and the non-linear interactions that are inherent to all cycling flows. Current findings in this field have and will continue to evolve the sport of elite cycling while also posing a multitude of potentially fruitful areas of research for further gains in cycling performance. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Abstract: This paper reports aerodynamic testing results of various styles of bicycle wheels across yaw angles of 0 to 30 degrees. Wheels considered include disc wheels, a bladed spoke wheel and various depth dished wheels. Testing has been completed in a three quarter open jet test section wind tunnel with a anthropomorphic mannequin and rotating front and rear wheels. Data is provided as to the influence of the wheel type on the overall drag and side force, and yaw and roll moment of the rider and bicycle combination. The results demonstrate that the wheel type has a significant effect on both the aerodynamic drag and stability of the bicycle system, and that evaluation of wheel aerodynamic performance should not be based on drag alone. [Copyright &y& Elsevier]

Abstract: The aerodynamic drag of a cyclist mannequin is measured in a ¾ open jet wind tunnel. The mannequin leg position is systematically varied over a complete crank cycle and aerodynamic drag measurements are taken every 15 degrees. The results show that rider aerodynamic drag is strongly affected by leg position with a difference between the maximum and minimum drag coefficients measured over a pedal cycle being approximately 15%. A small variation in cyclist frontal area is apparent over the pedal stroke, however the change in aerodynamic drag coefficient is identified as the dominant mechanism affecting cyclist drag. A series of flow visualization studies have been used to demonstrate the large effect that the position of the legs has on the flow around the entire body of the mannequin. It is observed that the flow regime is symmetrical for the low drag case and asymmetrical for the high drag case. This work highlights that the flow regime changes significantly throughout the pedal stroke of a cyclist, and consequently drag varies. This has implications in terms of analyzing cyclist aerodynamic performance as it highlights that multiple flow regimes should be considered. [Copyright &y& Elsevier]

Aerodynamics is an important factor affecting cyclist performance, as at the elite level 90% of rider energy is used to overcome aerodynamic drag. As such, much effort has been channeled into understanding the detailed flow around cyclists, since small gains can produce large rewards. Previous studies have shown that cycling aerodynamic drag is sensitive to leg position during the pedaling cycle; however, a systematic analysis comparing the impact of leg position between different riding postures is yet to be undertaken. To address this question, we compare the impact of leg position for two elite-level riding postures: the standard sprint and pursuit body positions. The comparison shows that the effect of leg position on drag is not consistent between the two riding postures, as the altered flow associated with different leg positions is influenced by the wakes from and proximity of other upstream or nearby components, such as the arms. This study reveals the inter-relationship between leg position and riding posture; and suggests that the flow associated with varied leg position should include surrounding geometrical components to obtain and understand the full aerodynamic impact. Practically, the results are valuable for optimizing the posture and improving skin-suit design for drag minimization. [ABSTRACT FROM AUTHOR]