HALF DISTANCE BOULDER TRIATHLON Swim (1.2 miles): Athletes start at the east boat ramp of Boulder Reservoir, swim counterclockwise, and exit at the west boat ramp. Average water temperature is 62°F (17°C). Bike (56 miles): The bike course is a 2-loop route with freshly paved roads. It begins at Boulder Reservoir, heads onto Diagonal Hwy towards Foothills Hwy, and features short rollers and a fast descent on rural Hygiene Rd. After looping back to Diagonal Hwy, athletes repeat the course. Run ...