On the day he won a record seventh Tour de France, Lance Armstrong expressed sympathy for "the cynics and the skeptics."
"I'm sorry that you can't dream big, I'm sorry you don't believe in miracles," he said in Paris, in July of 2005, on the verge of his first retirement.
"You should believe in these athletes, and you should believe in these people. I'll be a fan of the Tour de France for as long as I live. And there are no secrets – this is a hard sporting event and hard work wins it."
It was typical bravado from a Texan who had come back from cancer to lead a powerful American team at an event traditionally dominated by Europeans, winning more times than anyone in history. But as he triumphed – year after year, repeatedly blowing past rivals now known to have been doping – it became more difficult to believe he had done so by hard work alone.
After being diagnosed in 1996 with testicular cancer that had metastasized to his brain and lungs, Mr. Armstrong's later cycling feats had always been difficult to fathom. Although the prognosis was poor, he received aggressive treatment and the cancer went into remission.
Throughout his career, Mr. Armstrong always insisted he was clean, often invoking his victory over his cancer as a motivating force on the bicycle. In his biography, he said that "surrender, even the smallest act of giving up, stays with me. So when I feel like quitting, I ask myself, which would I rather live with?"
He approached doping accusations with the same conviction, defending himself vigorously and meeting allegations with threats of libel action. The energetic defence over the years makes all the more shocking his decision not to contest accusations by the United States Anti-Doping Agency, which took his move as an effective admission of guilt.
By not challenging the USADA allegations further in an arbitration process, Mr. Armstrong leaves himself open to the charge that he simply didn't want potentially damning evidence to be made public.
It is an astonishing fall from grace for a man who for years dominated one of the hardest sporting events in the world, raising millions for cancer awareness and inspiring a generation to take up cycling.
Mr. Armstrong began competing as a youth swimmer and then triathlete before switching his focus to road cycling. He won the world championship in 1993 and picked up a pair of stage wins in the Tours de France, one in 1993 and the other in 1995.
After beating cancer in 1996, he was training seriously by the start of 1998 and won his first three-week tour, the Vuelta a Espana, that year and then triumphed at the Tour de France in 1999. It was the start of a seven-year reign in cycling's most prestigious race.
Although the sport's purists sometimes found his domineering style boring, during those years fans were treated to a long-running rivalry with German Jan Ullrich and epic climbing duels with Italian Marco Pantani. Cycling gained mainstream popularity in North America, with television channels that normally wouldn't touch the sport carrying the Tour.
As Mr. Armstrong's fame grew, he dated musician Sheryl Crow, partied with celebrities and went riding with fellow Texan and then U.S. president George W. Bush.
But the shadow started to build early in his Tour dominance and never went away. A back-dated prescription was used to excuse the use of cortisone, which is otherwise restricted; former employees told troubling stories about what they had seen; and a testing on stored samples appears to show use of the banned blood-booster EPO.
The allegations polarized cycling fans.
Detractors fumed at what they perceived as a holier-than-thou demeanour during some of the sport's most drug-soaked days. But loyalists insisted he was innocent, often adding the vague insinuation that French envy was somehow at the root of the accusations, while claiming their hero simply worked harder than anyone else.
But then former teammates started to peel back the curtain with unseemly accusations of organized doping.
Mr. Armstrong now joins the long list of top cyclists whose names are formally tainted by association with drugs. Besides the Texan, the Tour was won by six men between 1996 and 2010. Two were proved to have been doping and stripped of their victories, two more were implicated but kept their titles and another, 1996 winner Bjarne Riis, admitted doping more than a decade after.
The International Cycling Union, which governs the sport, said that it was too late to punish Mr. Riis and urged him to return the yellow jersey given to winners. But it might prove harder to get Mr. Armstrong, the arch-competitor, to give up the symbols of his victories.
"I live for this jersey," Mr. Armstrong said at the 2003 Tour, according to Matt Rendell's book Blazing Saddles, the cyclist punching the seats of his bus for emphasis. "It's my life. No one's taking it away from me."