10 Seconds Flat

Boulder County, Colorado, United States

11.7 miles (18.8 km) · 7,078 ft elevation gain · Loop · trail · Route

10 Seconds Flat covers 11.7 miles across Boulder County, Colorado, United States. Runners face 7,078 feet of climbing with 7,034 feet of loss. The largest climb extends 1.2 miles, gaining 1,204 feet. The course averages 604 feet of vertical gain per mile. The course is 5% runnable, with the remainder requiring hiking on steep or technical sections. Trail comprises the majority of the course. Terrain difficulty is rated as mountainous. Difficulty is rated 48.9 out of 10, placing it in the 99.52th percentile. Popular among trail runners and hikers seeking Colorado adventures.