Ride 50 miles through Yellowstone National Park car free.
A Sasquatch ride!
http://www.nps.gov/yell/parknews/11018.htm
http://www.nps.gov/yell/planyourvisit/springbike.htm
http://m.billingsgazette.com/mobile-touch-2/?disableTNStatsTracker=1&asset=be6b0d3c-9c17-52f6-afc5-6b99cb64fd03#be6b0d3c-9c17-52f6-afc5-6b99cb64fd03
Unfortunately you'll have to wait until next year.