Before Tank Carder became a stud linebacker at TCU (and eventually a Cleveland Brownie), he was a stud BMX rider who won a world championship at age 9.
He was so good, he even got his own trading card.
Man I miss the 90s.
It was a short-lived career, though. According to The New York Times, he took a break from the sport and picked it up again, only to be seriously injured in a car crash that made him think he'd never play sports ever again. It's really an incredible story that you can read here if you're not familiar.