If you're into speed or new to triathlon, The Fleet Feet Sports SuperSprint Triathlon is made to order featuring a 375 meter (.25 mile) swim in Lake Michigan parallel to the beach, a 10 kilometer (6.2 mile) bike and a 2.5 kilometer (1.55 mile) run. The triathlon takes place at Foster Avenue Beach (Chicago's north side lakefront) on Saturday, August 29 in association with the McDonald's Kids Triathlon and the Chicago Triathlon multisport weekend. Foster Avenue Beach.