Flagstaff Mountain

The defining training climb of Boulder cycling and the most ridden road in Colorado. Starting from the mouth of Chautauqua Park, Flagstaff Road rises 500m over 5.8km at a punishing average of 8.6% — numbers that conceal the true character of the climb. The lower 2km average over 10% through a series of switchbacks cut into the red sandstone Flatirons, demanding a disciplined pace from the first pedal stroke. Above the halfway point the gradient eases marginally to 7-8% through pine forest before the final push to Flagstaff Summit at 2,106m. The views back over Boulder, the plains extending east to Kansas, and the Continental Divide to the west are among the finest in American road cycling. Every serious Boulder-based rider has a personal best on this climb. Pro teams use it as a benchmark test; recreational riders come to find out what altitude does to their legs. The road surface is excellent and maintained to a higher standard than most city park roads.