Team Sky have dismissed suggestions that their dominance of Saturday's opening time trial in the Tour de France was down to an illegal skinsuit.
Team Sky riders made up four of the top eight on the 14 kilometre course around Dusseldorf, with Geraint Thomas taking the race leader's yellow jersey with his first career Tour stage win.
But professor Frederic Grappe, performance director for the French FDJ team and a sports science expert, claimed after the stage that Sky's skinsuit had Vortex air bubbles woven into the fabric against UCI rules.
Grappe claimed the material could have been worth "18 to 25 seconds" for each rider. "The rule is very clear. Any aerodynamic addition to the jersey is banned. Sky have clearly infringed," he said. But Team Sky's sports director Nicolas Portal said Grappe had got it wrong.
"We haven't cheated," he said. "Everything is legal and the equipment was validated by the race commission. We wouldn't have taken the risk of losing the Tour from the first stage by cheating. Other teams use this material, but we're the ones being attacked.
"We're not infringing the rules because the Vortex isn't added to the jersey, it's part of it -- that's different."
Thomas won the time trial by five seconds from BMC's Stefan Kung, with Sky's Vasil Kiryienka, Chris Froome and Michal Kwiatkowski also in the top eight on sodden roads in Dusseldorf.
Thomas faced questions about the suit both after the time trial and after Sunday's stage two, in which he retained the yellow jersey despite being caught up in a crash.
"You can borrow the skinsuit if you want," the Welshman said. "See what time you do."
He added that he had worn the same skinsuit for a time trial in the Giro d'Italia in May without issue.
UCI regulations state: "Garments must not be adapted in any way such that they diverge from their use purely as clothing. The addition of any non-essential element or device to clothing is prohibited."
Race jury president Philippe Marien cleared Sky, saying the suit did not infringe rules. "On the basis of the regulations, I did not have a legal reason to prohibit this equipment," he said in comments reported by L'Equipe.