Riblon Wins Stage of Dual Ascents Peter Dejong/Associated Press Christophe Riblon of France rallied in the closing miles to win the 18th stage of the Tour de France. ALPE D'HUEZ, France - The 100th Tour de France had been billed as a battle between a rising star and a fading one: Christopher Froome versus Alberto Contador, the commanding leader of this year's Tour against a once-dominant Grand Tour racer who has struggled all year. Stage 18 seemed custom-made for their rivalry. For the first time in Tour history, the riders would ascend the daunting Alpe d'Huez twice, with a treacherous descent from the Col de Sarenne in between. As if to fuel the prestage drama, Froome had almost crashed into Contador during a furious downhill chase on Stage 16, and later chided the Spanish rider to ride more safely. As if on cue Thursday, Contador sped away from Froome during the descent from Col de Sarenne, all but daring Froome and his teammates on Sky Procycling to follow their daring lead. It took awhile, but they eventually did, catching Contador and then leaving him behind as the race turned up Alpe d'Huez for the second time. At the finish, Froome extended his lead over Contador to 5 minutes 11 seconds. Nairo Quintana, a Colombian climbing sensation on the Movistar team, gained more than a minute on Froome and moved into third place. The stage was won by Christophe Riblon, a French rider on Ag2r-La Mondiale, who caught the weary American Tejay van Garderen of BMC less than a mile and a quarter from the finish. Van Garderen, who has seen his fortunes improve after a miserable initial two weeks on the Tour, finished the stage in second, nearly a minute back. Though he solidified his lead over Contador, Froome showed a certain vulnerability on the stage. He had crushed his top challengers twice on mountain stages in this Tour. But in the final stages Thursday, he motioned repeatedly to his team car for help, until his durable teammate Richie Porte delivered him some food. As Froome slowed to eat, Quintana and Joaquim Rodríguez of Katusha distanced him. Froome was given a 20-second penalty for eating outside the designated feed zone. Extraordinary performances in Grand Tour races almost always prompt questions about doping in the post-Lance Armstrong era, and that has been the case for Froome throughout this Tour. On Thursday a reporter turned the issue on its head, asking the rider whether his sugar fit on Alpe d'Huez suggested that he was human after all. "'It's crazy hearing people talk like this,'" Froome replied. 'Any athlete can have a sugar low at the end of a race.' "'I know what I'm doing is right, and I'm extremely proud of what I've done to get here,'" he added. 'No one can take that away from me.' Cycling reporters and scientists who monitor cycling performance data for signs of doping raised questions about Froome's accelerations from the peloton in the Pyrenees and on Mont Ventoux earlier in the race. In response to those questions, Sky allowed the French sports newspaper L'Équipe and a sports scientist, Fred Grappe, to analyze Froome's power data from six races that involved 18 ascents, including some from this Tour. They did not, however, release the data, which included doping test results, to the public. In the article, Grappe, a trainer with the FDJ team, said he had found no deviations in the rider's power output that would clearly indicate the use of performance-enhancing substances. The power he was producing on those rides, in other words, was within the realm of human physiology. "'Basically it is to say these performances are very good, strong, clean sporting performances,'" Froome said after the stage. Ross Tucker, a South African physiologist who has been a leader in calling on professional cycling teams to release such data publicly, said Grappe is a "respected" scientist and called Sky's move "'a great step forward for the sport," adding, "I'd love for all the teams to do it." He added that the times up Alpe d'Huez Thursday were not particularly fast - a good thing, in the minds of antidoping watchdogs. "If Froome had flown away from everyone and finished faster than Quintana, then it would still be leaning to the suspicious side," he said. "This was a more "real" performance."