Dumoulin power data reveals true story of Vuelta a España ride

Tom Dumoulin has this week released his power files from the 2015 Vuelta a España, where he surprised followers by coming close to the overall classification victory.

Giant-Alpecin's Dumoulin only failed on the final mountain day, slipping out of the lead and sliding to sixth place overall behind Fabio Aru (Astana), who won the race.

"I know of no good reason not to share my data," Dumoulin told Dutch newspaper AD.

"Only the data from my [time] trial, I'd rather not make that public. Others can read things on my aerodynamics. The rest everyone should know."

Dumoulin's team Giant coach, Adriaan Helmantel told Cycling Weekly last week that the Dutchman pushed around 6.0 watts/kilogram for 25 minutes on Ermita de Alba, the last climb on stage 16, the third day of three mountain stages. The article today, however, gives the exact numbers over the entire Vuelta.

The six-foot-one, 70kg rider pushed 459.6 watts over 8-29 minutes, or 6.6w/kg on the first summit finish, where he placed second to Esteban Chaves (Orica-GreenEDGE).

He reached a max of 508.2 watts over 5-55 minutes, 7.0w/kg, on the short climb at the end of stage six. When he won ahead of Froome in stage nine, he averaged 6.6w/kg.

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Dumoulin suffered on the longer climbs though. When he lost the Vuelta to Aru on the final two passes in stage 20, he averaged 5.9 over 16-48 minutes and 5.2 over 30-27 minutes.

The newspaper published an image with the full set of numbers alongside its article.

As Dumoulin does with his time trial numbers, others want to keep their data files to themselves. Chris Froome and Team Sky fear that their rivals could study and plan attacks accordingly based on the information.

Critics say that high numbers could point to doping. During the Tour de France, an expert at France 2 "surprised" Team Principal David Brailsford when they estimated Froome rode at 7.04w/kg during his victory on stage 10 of the race, prompting Sky to release some numbers.

On the same La Pierre-Saint-Martin climb in question, Sky's head coach Tim Kerrison said that Froome rode 5.78w/kg.

Brailsford suggested that instead of publicising the numbers, cycling's governing body should set up an independent group to study everyone’s data to create a "power passport" as a way of further controlling the sport.

Froome, asked about critics' speculation on the second rest day, said, "I'm not sure if numbers will fix everything."

In the case of Dumoulin's surprising Vuelta ride, team Giant said that the numbers show it is "not strange what happened."

Helmantel explained that the training at altitude in Sierra Nevada, Spain, and in Livigno, Italy, after crashing out of the Tour de France on stage three, paid off.

He added that Dumoulin's ride was also possible due to a lack of strong competitors. Froome and Tejay van Garderen (BMC Racing) abandoned with crashes, Vincenzo Nibali (Astana) was disqualified on the second day, and Nairo Quintana (Movistar) fell sick. Other riders, he said, were not at their best after the Tour.