Sarah Hammer rides to win the women's individual pursuit. Hammer won the race at the World Track Cycling Championships earlier this year in Bordeaux, France.

Carson, Calif. ? Sarah Hammer never forgot her first race. She pedaled her Big Wheel tricycle to a huge lead, got bored by the lack of challengers and waited for the other 2-year-olds to catch up.

They never did.

That’s how many races still go for Hammer, though these days she doesn’t give rivals a chance. Three years ago, she was struggling as a cell phone saleswoman after retiring from bike racing because of burnout. She’s since returned to win consecutive world championships in one of track cycling’s most grueling events, and should head into Beijing next summer as one of the United States’ top hopes for Olympic gold.

“It’s a lot of pressure,” Hammer said. “But that’s not a bad thing. It’s what drives me.”

It’s also what brought her back into the sport that she quit as a 20-year-old.

Outside of the cycling world, Hammer is almost unknown. She’s never been on the Olympic stage and won’t head into Beijing with the hubbub that follows the likes of swimmer Michael Phelps, sprinter Justin Gatlin or gymnasts Paul and Morgan Hamm.

Yet when it’s time to identify gold-medal favorites, she may belong in that group.

“When I say she’s in a class by herself, I don’t just mean in the United States,” said Pat McDonough, the director of athletics for USA Cycling. “She’s been the class of the field in the world for the last couple of years. She always had the talent. She got away from the sport, decided that selling bagels wasn’t what she wanted to do. But the thing about cycling is, you need the ability to hurt. And she’s got that.”

The story goes like this: About a year after thinking she was done with bike racing, Hammer was sitting on her couch watching the 2004 Olympics from Athens, specifically the 3,000-meter individual pursuit, where New Zealand’s Sarah Ulmer won the gold medal in world-record time.

Hammer immediately felt the twitch to get back on the bike. A couple of weeks later, she told boyfriend Andy Sparks that she wanted to resume training with an eye on the ’08 games.

“I knew you would,” Sparks replied. “I knew you would all along.”

They went to work, Sparks serving as Hammer’s coach, and surprised more than a few onlookers by showing up and winning at the 2005 USA Cycling national championships. The first world title in the 3,000 individual pursuit – her specialty, a 31â2-minute session of furious pedaling that leaves riders in such pain that they often have trouble standing afterward – soon followed, and victories have kept piling up since.

“It’s a game for some of our guys to see if they can hang with her, even in her warm-ups,” said Michael Blatchford, one of the top U.S. men’s sprinters on the velodrome. “Most people can’t. And that’s the endurance guys who have trouble. No sprinter is going to hang with her, that’s for sure.”

Few people around the world can hang with Hammer on the track these days.

She starting riding competitively as an 8-year-old, won a junior national title four years later, and eventually moved to the Olympic Training Center in Colorado Springs, Colo., honing her skills as a road cyclist. Hammer got a job with a pro team, but the results simply weren’t what she wanted.

So she retired. Didn’t get on a bike, even recreationally, for 10 months. Got a job in a bagel shop, hated it, then got a job in a cell phone store and hated that, too. Hammer says she was a bad saleswoman, and she’s probably right – to this day, she can’t sync her e-mail with her BlackBerry.

Then she watched someone else win Olympic gold, saw another nation’s flag hoisted and anthem played in the medal ceremony, and decided that bike racing never meant so much.

“This is who Sarah Hammer is,” said Sparks, who became Hammer’s fiance in February and has remained her coach. “She quit, and she burned out because she no longer remembered why she wanted to do this. Then she got to remember why she loves this sport, and as soon as you come to that realization, an enlightening moment about what this is about, that fire was lit again.”