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Grégoire P. Millet, Cyrille Tronche and Frédéric Grappe

Purpose:

To use measurement by cycling power meters (Pmes) to evaluate the accuracy of commonly used models for estimating uphill cycling power (Pest). Experiments were designed to explore the influence of wind speed and steepness of climb on accuracy of Pest. The authors hypothesized that the random error in Pest would be largely influenced by the windy conditions, the bias would be diminished in steeper climbs, and windy conditions would induce larger bias in Pest.

Methods:

Sixteen well-trained cyclists performed 15 uphill-cycling trials (range: length 1.3–6.3 km, slope 4.4–10.7%) in a random order. Trials included different riding position in a group (lead or follow) and different wind speeds. Pmes was quantified using a power meter, and Pest was calculated with a methodology used by journalists reporting on the Tour de France.

Results:

Overall, the difference between Pmes and Pest was –0.95% (95%CI: –10.4%, +8.5%) for all trials and 0.24% (–6.1%, +6.6%) in conditions without wind (>2 m/s). The relationship between percent slope and the error between Pest and Pmes were considered trivial.

Conclusions:

Aerodynamic drag (affected by wind velocity and orientation, frontal area, drafting, and speed) is the most confounding factor. The mean estimated values are close to the power-output values measured by power meters, but the random error is between ±6% and ±10%. Moreover, at the power outputs (>400 W) produced by professional riders, this error is likely to be higher. This observation calls into question the validity of releasing individual values without reporting the range of random errors.

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Paul F.J. Merkes, Paolo Menaspà and Chris R. Abbiss

with the hands in the drops. However, other variables like seated and standing, head high or low, or elbows tucked or not were not controlled. These small changes in riding position are likely to affect aerodynamic drag (product of drag coefficient [Cd] and frontal area [A]: CdA). 18 – 22 The Velocomp

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Samuel Sigrist, Thomas Maier and Raphael Faiss

aerodynamic drag 15 in the slipstream, allowing partial recovery from the leading efforts. Practically, every transition during the race requires the lead rider to cover a longer distance while continuously pedaling to keep momentum when using the velodrome bankings to gain potential energy in the curve that

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Ana B. Peinado, Nuria Romero-Parra, Miguel A. Rojo-Tirado, Rocío Cupeiro, Javier Butragueño, Eliane A. Castro, Francisco J. Calderón and Pedro J. Benito

influenced by several limitations such as aerodynamic drag, rolling resistance, cyclist mass, hill gradient, gear ratio, or total distance. 10 , 13 Power output and cadence during uphill segments of the Tour de France have been described. 14 During ascents, cyclists have to sustain a mean power output of