ASPEN, Colo. (AP) For a few hours, Lance Armstrong was back in his element on a bike and in a race.

No controversies, little fanfare.

The escape Saturday into the mountains around Aspen, Colo., comes a day after the U.S. Anti-Doping Agency disciplined Armstrong with a lifetime ban from professional cycling and vacated his seven Tour de France titles after deciding he used performance-enhancing drugs.

There were only a handful of fans at the start of the Power of Four mountain bike competition, a 36-mile trek that includes plenty of climbing.

Asked if he was ready, Armstrong smiled and said, "I hope so. ... This is going to be hard for all of us."

Decked out in black and gold and sporting a Livestrong emblem on his jersey, Armstrong tinkered with his bike and gave a kiss to girlfriend Anna Hansen before pedaling off.

His busy weekend includes a marathon Sunday. He may be banned from cycling, but it hasn't diminished his passion for competition.

These weekend races may have to suffice.

Armstrong, who retired a year ago and turns 41 next month, said Thursday he would no longer challenge USADA and declined to exercise his last option by entering arbitration. He denied again that he took banned substances in his career, calling USADA's investigation a "witch hunt" without any physical evidence.

USADA said its evidence came from more than a dozen witnesses "who agreed to testify and provide evidence about their firsthand experience and/or knowledge of the doping activity of those involved in the USPS conspiracy," a reference to Armstrong's former U.S. Postal Service cycling team.

The unidentified witnesses said they knew or had been told by Armstrong himself that he had "used EPO, blood transfusions, testosterone and cortisone" from before 1998 through 2005, and that he had previously used EPO, testosterone and Human Growth Hormone through 1996, USADA said. Armstrong also allegedly handed out doping products and encouraged banned methods and used "blood manipulation including EPO or blood transfusions" during his 2009 comeback race on the Tour de France.

USADA chief executive Travis Tygart described the investigation as a battle against a "win-at-all-cost culture," adding that the International Cycling Union was "bound to recognize our decision and impose it."

Fans defended Armstrong on Twitter, insisting his work with Livestrong trumps what he accomplished on a bike. His success helped sell millions of "Livestrong" yellow plastic bracelets as he promoted cancer awareness and research. He's raised nearly $500 million since the Lance Armstrong Foundation started in 1997.

On Friday alone, the foundation said it received 400 donations that totaled around $75,000.