Estimation of an Elite Road Cyclist Performance in Different Positions Based on Numerical Simulations and Analytical Procedures

Abstract

The aim of this study was to use numerical simulations and analytical procedures to compare a cyclist's performance in three different cycling positions. An elite level road cyclist competing at a national level was recruited for this research. The bicycle was 7 kg and the cyclist 55 kg. A 3D scan was taken of the subject on the competition bicycle, wearing race gear and helmet in the upright position, in the handlebar drops (dropped position) and leaning on the elbows (elbows position). Numerical simulations by computer fluid dynamics in Fluent CFD code assessed the coefficient of drag at 11.11 m/s. Following that, a set of assumptions were employed to assess cycling performance from 1 to 22 m/s. Drag values ranged between 0.16 and 99.51 N across the different speeds and positions. The cyclist mechanical power in the elbows position differed from the upright position between 0 and 23% and from the dropped position from 0 to 21%. The cyclist's energy cost in the upright position differed 2 to 16% in comparison to the elbows position and the elbows position had less 2 to 14% energy cost in comparison to the dropped position. The estimated time of arrival was computed for a 220,000 m distance and it varied between 7,715.03 s (2 h:8 min:24 s) and 220,000 s (61 h:6 min:40 s) across the different speeds and positions. In the elbows position, is expected that a cyclist may improve the winning time up to 23% in comparison to he upright and dropped position across the studied speeds.

The Drag Crisis Phenomenon on an Elite Road Cyclist—A Preliminary Numerical Simulations Analysis in the Aero Position at Different Speeds

“…However, it is yet unclear if the phenomenon under appreciation is present when testing cyclists in the aero position. If so, it can explain, at least to some extent, drag variations as noted beforehand [ 24 , 25 , 26 ]. A deeper insight into the drag crisis and its effect on drag force can also be an aid to end-users.…”

“…The turbulent kinetic energy and dissipation rate were defined as first order upwind [ 12 ]. The convergence occurred automatically in the Ansys Fluent 16.0 [ 24 , 25 , 26 , 27 ].…”

“…The numerical simulations allows us to obtain the drag and the drag coefficient from Ansys Fluent Software [ 24 , 25 , 26 , 27 ]. For the drag force, Equation (1) was used: where F d is the drag force, C d represents the drag coefficient, v the velocity, A the surface area and ρ is the air density (1.292 kg/m 3 ) [ 24 , 25 , 26 , 27 ]. C d is given by Equation (2): …”

“…Indeed, the drag crisis might occur in different bodies in sports settings just as in a bicycle–cyclist system. Forte et al [ 24 ] suggested assessing C d across different speeds, even though, at least in sports sciences, analysts and researchers are prone to assume that C d is kept constant across a range of speeds [ 25 ].…”

“…It is a standard procedure to test cyclists in the aero position [ 24 , 25 ]. However, it is yet unclear if the phenomenon under appreciation is present when testing cyclists in the aero position.…”