Lance Armstrong, banned from cycling for life after declining to fight charges leveled by the US Anti-Doping Agency, apparently will not be going quietly.

“Excited to be racing the #poweroffour tomorrow here in @AspenCO,” Armstrong tweeted on Friday, hours after USADA said it was stripping Armstrong of his seven Tour de France titles and banning him from competition for life for multiple doping violations.

On Thursday Armstrong said he would not seek arbitration, triggering the sanctions by USADA. “There comes a point in every man’s life when he has to say ‘enough is enough.’ “For me, that time is now,” said Armstrong, adding he would have nothing further to say about doping.

Instead he waxed enthusiastic about the Power of Four mountain bike race for individuals and relay teams in Colorado, which includes racing on four distinct mountains in the Aspen-Snowmass ski area.

“9000 vert in just 36 miles!” Armstrong tweeted, a reference to the challenge posed by a course that features an 11,000-foot vertical gain and 9,000-foot vertical drop. For good measure, Armstrong tweeted, he is also planning to run in a marathon on Sunday. His spokesman Mark Higgins said neither event comes under USADA’s jurisdiction.

Lance Armstrong, who has been stripped of his seven Tour de France titles and banned for life, was regularly tipped off over drugs tests, a leading French anti-doper claimed on Saturday.

The American went through his entire career without failing a drugs test, but Michel Rieu, the scientific advisor at France’s anti-doping body (AFLD) told Le Monde newspaper that Armstrong was warned when the testers were about to call. Rieu said: “The testers found it difficult to carry out checks without Lance Armstrong benefitting from a delay of 20 mins. He was warned before any controls.

In 20 mins, a lot of manipulations are possible. Without information from police or customs, it was impossible to fight this way.” Rieu claimed Armstrong has many supporters inside the sport, to help him in need. “This support went beyond the UCI (International Cycling Union) and the International Olympic Committee.

Armstrong was surrounded by scientific physiologists some of which were discarded later. He had considerable resources to protect and implement logistics. There were rumours he transferred blood from USA in his private jet,” said Rieu.