Cirque Series - Arapahoe Basin
Keystone, United States • 5 Sep 2026
Cirque Series - Arapahoe Basin
The Cirque Series event at Arapahoe Basin in Keystone, Colorado takes place on September 5, 2026. The course is a single mountain loop of 9.4 miles with 2,211 ft of vertical gain. The start is at Mountain Goat Plaza at about 10,780 ft and the route climbs past High Noon parking, Black Mountain Lodge and out toward Zuma Cornice before summiting Little Lenawee peak and returning to Mountain Goat Plaza for the finish.
The route uses established trails in the White River National Forest and combines summer road, new singletrack uphill sections, the Half Moon Vista singletrack on the descent, the Argentine North Fork trail, and a final mountain bike singletrack into Mountain Goat Plaza. Hydration is provided at two on-course aid stations and at the finish line. Every runner is subject to a strict cutoff at Black Mountain Lodge Aid Station #1. The course is marked and participants are advised to follow flagging and standard trail safety procedures.
The event is capped at 700 runners and includes multiple entry categories: Sport, Expert and Pro, plus volunteer positions. Per-race prizes are listed for each category including cash awards for Pro placings and gear awards for Expert and Sport placings. Additional recognitions include Grom, OG, Lexie and Middle of the Pack awards. Timing is by a disposable chip on the bib and early packet pickup is available in Boulder the day before. Visit the organization's website for the most recent information.