Chainrings = Olympic Rings

BMX racing has been around since the 1970s, when preteen hooligans started racing each other around dusty lots in California. Some 30 years later, the sport made its smash-hit Olympic debut. This caused a worldwide media frenzy, and even Kathie Lee Gifford of "The Today Show" got in on the action by pedaling around on a BMX bike during a show.   (Photo: Bob Thomas / Getty Images)