The Breckenridge 100 is an ultra-endurance mountain bike race held annually in mid July in Breckenridge, Colorado. The race offers two distance classes, 100 miles (160 km) and 100 km (62 mi). No awards are presented to those doing the shorter version, it simply offers an easier alternative for those riders not ready to race the full 100 miles. The race has been one of the stops of the National Ultra Endurance Series since 2006.
The sprawling course is nestled between three ski resorts and features a distinct cloverleaf format of three loops that each begin and finish in Carter Park, adjacent to historic downtown Breckenridge. The race crosses the Continental Divide of the Americas three times, once at Wheeler Pass at an elevation over 12,400 ft and twice at Boreas Pass at an elevation of 11,492 ft. The course climbs a total of 13,719 feet, and includes backcountry trails, roads, double track, bike paths, and high mountain stream crossings.