Armstrong is bidding for a record sixth straight Tour de France (search) title, but had planned to ride for the United States next month at the Summer Games.
"I've thought a lot about this and the answer is, I shouldn't even say 'probably not,' I should say 'no,'" Armstrong said Thursday when asked about his plans following the Tour de France on July 25.
Armstrong was 13th in the road race at the 2000 Sydney Games and won a bronze medal in the time trial — his first medal in three Olympics.
The Texan said he spent two months away from his children in the spring and another three months apart before the Tour de France, cycling's three-week showcase.
"It's really hard to do, and so I want to go home," he said. "I've done the Olympics many times, and if I don't have 100 percent motivation for something that's an important event, a very important event, then I don't want to take somebody else's spot."