If sport is art then cycling at the Tour de France is often a masterpiece -- a tightly-knit pack of riders scaling a mountainous French canvas and testing, like all great artists, the limits of human possibility.
But draw your eye closer to the surface, and you'll see that so much of it has been counterfeit -- a product of illegal doping that boosts performance but taints the sport.
ABCNEWS.com spoke to several former pro riders -- some of whom admitted to doping -- who explained the temptation to dope as a make or break career decision for anyone who hopes to remain competitive in world class professional cycling.
After years of suspensions and suspicions surrounding many of the tour's top riders, including last year's winner, Floyd Landis, illegal doping allegations have virtually destroyed this year's Tour de France. Two of the race's highest-profile riders, the leader and projected winner Michael Rasmussen and another early favorite, Alexandre Vinokourov, were kicked out mid-race, casting doubt on the validity of the sport and questions about the Tour's future.
It's an incontrovertible fact about cycling: Doping works -- a stark reality that influences the professional lives of many riders.
The former pro riders who spoke to ABC News said that most cyclists -- highly trained athletes who race across the countryside at high speeds in such close proximity that one awkward move could send the whole pack falling -- face a difficult and extraordinarily solitary choice: Dope or go home.
Though they travel in packs on the course, after the race there is little cooperation. Cyclists have no union that might limit or control the testing of riders. While rumors of doping fill the air, riders rarely speak of their doping decisions to their own team members, much less to other riders or the fans.
But with the dismissal from the Tour this week of two racing teams, the illusion of order and authenticity has been violently lifted from the peloton.
The former riders, including two Tour teammates of Lance Armstrong, spoke with surprising candor about the difficult and lonely culture of professional cycling, with some admitting that their secret decision to dope helped them stay competitive -- while others said their choice not to dope effectively forced them into early retirement.
Brian Walton could have been a contender. A 1996 Olympic silver medalist, he went to Europe for four years to compete in the top pro circuit. Rumors of doping racers were everywhere, but Walton refused to take performance enhancers. He said he kept getting stronger, but kept falling further behind in the peloton.
The choice, he said, was simple: He could either dope, or he could go home.
"The writing was on the wall for me," Walton said.
For riders like Walton, a refusal to dope often spells an early retirement. And that's exactly what happened. Walton, who is a cycling coach today, said he returned home rather than compromise his values.
Jonathan Vaughters and Frankie Andreu were contenders. They were both part of the 1999 U.S. Postal Service team that helped Lance Armstrong win the first of seven consecutive Tour victories. They both, it seems, may have cheated to get there.