TdF 2013 - Part II

The average speed of Tony Martin (54.2 Km/h) was indeed very high in yesterday's TT, but it was Froome's performance that surprised the suiveurs: 54.0 Km/h, with the rivals nearly 3 km/h slower.


While the usual malicious comments are being wasted around, repeating adjectives already used after the team time trial done at 58 km/h, I remind that in cycling, in the flats, the speed is not a very significant parameter, heavily influenced by the course (more or less straight), the wind direction, the type of asphalt, etc.

Technical materials are constantly evolving: apart from bikes frames and aero helmets, it is especially the new bodysuits textures and fabrics that significantly increase the speed at the same watts.


It is risky to estimate power outputs of athletes engaged in time trials on flat courses: Claudio Ghisalberti (Gazzetta dello Sport) ventured into assessments that reported as "pseudo-science": 480w average for Martin and 470w average for Froome.

How he arrived at these numbers is not known, but the reporter adds: Froome <i>"has 18% more power than their rivals."</i>


Now, assuming the aerodynamic efficiency to be equal for all riders (something that IS NOT...), considering the square speeds, the difference in power would be represented as follows:


Froome: 54.0 Km / h - 2916 (v2)

Porte: 52.3 - 2738, -6.5%

Mollema: 51.3 - 2635; -10.6%

Valverde: 51.2 - 2619; -11.3%

Contador: 51.1 - 2613; -11.3%

Evans: 50.8 - 2580; -13.1%

Quintana: 49.6 - 2456; -18.7%


In the last 5 km of the climb towards Aix 3 Domaines, from the moment of Froome's attack, the differences were smaller (but still very significant):


Porte: -5.5%

Valverde: -7.5%

Mollema: -7.6%

Contador: -11.5%

Quintana: -11.5%


Froome's attitude towards time trials is well known, but these differences between climbing and TT performances cannot be explained solely by the difference in body weight among athletes.

Contrary to the large majority of cyclists, Froome (but also Wiggins) is climbing with higher cadences (100-110 RPM) than in TT's (90-100 RPM), where he prefers to push important gears, perhaps also due to the use of longer cranks.


The extreme thinness, even with a significant reduction in lean body mass, evidently does not take away the power in his pedaling, which is particularly fluid, probably due to a reduction of internal friction and the cost of "spinning the legs."

11 Jul 2013