When students at Bay High School, in Bay Village, Ohio, organized their Bike to School Challenge in spring 2008, no one anticipated the response. "On the first day, 363 kids signed up and we were scrambling to keep up," says Scott Cowan, owner of Century Cycles in Ohio and the event's mastermind. "By the end of the three-week period, 550 students had participated." The program expanded this year  to include the middle school; 960 students biked the first day. "We're effecting a cultural change," Cowan says.