Urban Extreme

Who needs the mountains when you've got the Sears Tower? Why hit the slopes when you've got the local shopping mall? The newest fad in extreme sports is urban adventure racing, in which teams compete to scale buildings, scooter through busy intersections and dart on foot through crowded stadiums. Chicago was host to the first one, the 24-hour "Wild Onion," two years ago, and is getting ready for its third race this weekend. The 600 participants won't have much time to train: the course is a secret until two hours before the start.

--By Wendy Cole and Sean Gregory


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