Image 1 of 5 Chris Froome (Team Sky) wears the yellow jersey on the start line in Bourg-de-Péage Image 2 of 5 Yellow jersey Chris Froome (Team Sky) races stage 16 Image 3 of 5 Chris froome rides in the bunch during stage 15. (Image credit: Tim de Waele/TDWSport.com) Image 4 of 5 Chris Froome checks the time gaps at the finish. (Image credit: Tim de Waele/TDWSport.com) Image 5 of 5 Three time winner Greg LeMond at the presentation (Image credit: Fotoreporter Sirotti)

Amid all the speculation about the validity of Tour de France leader Chris Froome's performances, three-time Tour champion Greg LeMond assured that the Sky rider's performance is 'within the realm of human performance'.

Ahead of Froome's spectacular ride on the first Pyrenean mountain finish in La Pierre-Saint-Martin, a video surfaced online that overlaid Froome's supposed power data onto footage of the 2013 Mont Ventoux stage of the Tour de France, where Froome dropped Movistar's star climber Nairo Quintana in a similar manner to this year's stage 10.

Froome's power was estimated to be approximately 6 watts per kilogram on the climb of the Mont Ventoux, values that LeMond says are reasonable, especially in comparison with the power numbers riders were pushing back in the era of rampant EPO use, where race leaders were putting out up to 7 watts per kilogram. But, LeMond said on Eurosport, "I don't think you should ever make that judgement off of one climb", and called for a longitudinal study of power data combined with the biological passport to measure performance.

"You have to combine the [physiological] testing with the passport. Can people do what Chris did on the first mountain stage? I think it was 6.1 watts per kilo, which I think that's within the realm of human performance."

Team Sky has demonised Antoine Vayer, the former Festina team trainer who made Froome's data public, but LeMond agreed with Vayer's assertions that there should be nothing secret when it comes to race data.

"I talked to him ... he's just saying release the data," LeMond said. "I looked at it, and I didn't really see a whole lot to be worried about and so, and I think he's just pushing for transparency. Not to critique Brailsford or anybody at Sky but when you hear marginal gains, this is kind of what [Lance] Armstrong used in the past, so that kind of brings up a little bit of sensitivity."

Team Sky has not publicly released Froome's power data, but LeMond said it is easy to estimate given the data of other riders who have posted their power numbers on public forums. LeMond stressed that it is important for teams to make the actual power data from the meters available. Estimates (such as Michele Ferrari's VAM, or speed of elevation gain) do not take into account factors such as rolling resistance, temperature, wind, etc.

To judge whether or not a performance is 'human', one must look at these numbers across many days of racing.

"Everybody has got to understand, it's not just a watt for a split second, what we're looking for is long-term, over 20-30 minutes or 40 minutes at aerobic capacity, as close as you can get to your VO2 max ... all the world-class athletes are trying to get as close as we can to our VO2 max, that's a stable output when you can do that for higher work loads, not for just 30 minutes but repeat, even an hour and a half over a day's stage, that's what makes the difference," he said.

"That's the best indicator," LeMond said. "Ultimately, it doesn't matter if it's one long stage or short stage, ultimately somebody's going to have maximum watts per kilo, and if you record that enough, it's no different than a passport profiling, you'll get to see if these rides are consistent."

LeMond thinks the UCI should use all the information available to keep up with riders' performances.

"This is not about Chris Froome, or anybody, it's more about the tools are there with the UCI, the Tour de France. It's not just about one rider, it's nobody likes to have speculation," LeMond said, adding that physiological testing should be done across the entire pro peloton. "Pro teams are all doing it right now, so it's not really that difficult to do."



