Disgraced Landis retires from cycling
"I'll never start on a line on a road and try to get to another line on a road faster than another guy. That's over," Landis, 35, told ESPN.com.
Landis won the Tour in 2006 but failed a dope test for testosterone during the race and was stripped of the title.
He denied any wrongdoing until last May, when he admitted to doping and accused former team mate Armstrong, a seven-times Tour champion, and others of doping when they were both riding for the US Postal team.
Landis took part in a few races in 2010 as an independent rider but failed to secure a proper contract.