Data “not far from reality, but often a little overestimated”: can we really calculate the watts per kilo of riders in the Tour de France?

For some, like Kévin Vauquelin, there's no need for complicated equations; everything is on Strava. "My personal opinion is that it would be good if a lot of riders did the same thing; it would avoid the barroom discussions," says his coach, Kevin Rinaldi. But Tadej Pogacar and the peloton's top dogs don't make their wattage data public. So others take it upon themselves to try to calculate it. On social media, several accounts publish estimates of performances using standard watts (calculated for a 70 kg rider) or watts per kilo (power output in relation to the rider's estimated weight) as the unit. Depending on the result, they conclude whether a performance is "normal" or "abnormal."

Can we really calculate a rider's power without their sensor data? The question is stirring up controversy in the industry, especially since the figures put forward for some riders are enormous, sometimes unprecedented outside the EPO era, or indicate dazzling progress. From the peloton, Alex Baudin, who publishes his watts, noted that the data for riders he knows "were not far from reality, but often a little overestimated." Jean-Baptiste Quiclet, performance director at Decathlon-AG2R La Mondiale, finds the undertaking too delicate, "because you have to take into account the extrinsic (equipment, environment, weather conditions, etc.) and intrinsic performance of the rider," that is, the real efficiency of their pedaling. "It is very confusing to compare generations given the evolution of equipment," he adds.

"When we compared our calculations with the figures from a sensor, the margin of error was only 2% max."

Alban Lorenzini, a former engineer, himself a coach, and owner of an account that looks into these wattage issues, believes that "the estimates are reliable. There may be small variations, linked to the rider's weight. But when we compared our calculations with the figures from a sensor, the margin of error was only 2% max. We use IGN maps for slopes, Infoclimat for weather stations, we take into account the weight of the rider, the bike, its aerodynamics, the road's efficiency, we modeled the slipstream... And when the conditions aren't right, we don't calculate."

Last year, after climbing the Plateau de Beille , Jonas Vingegaard gave credit to the work of the "watt hunters" by describing the extraordinary figure of 6.85 W/kg calculated by the Lanterne Rouge website as "very precise." During the crossing of the Pyrenees, the calculators will be out again. And until the official data is published, the debate will continue.