Lean Horse Ultra
Custer, United States • 31-1 Jul-Aug 2026
Lean Horse Ultra Marathon
The Lean Horse Ultra Marathon takes place on the George S. Mickelson Trail in the Black Hills near Custer, South Dakota. The 2026 event is scheduled for July 31 to August 1, with registration closing July 12, 2026. The race was first held in 2005 and includes a sanctioned 100 mile event.
The trail surface is crushed limestone and the route follows an old railroad bed, producing extended gentle climbs along the course. Average August daytime temperatures for the area are a high of 79 degrees and a low of 53 degrees.
Event distances include individual and team options across multiple lengths. Organizers describe the course as non technical and rails to trails in character. A 30 mile Black Hills CrossFit Edition is offered with singles and relay teams.
- 100 Mile
- 100 Mile Relay up to 5 runners
- 50 Mile
- 30 Mile
- 20 Mile
- 30 Mile Black Hills CrossFit Edition singles or teams of 3 or 6
The event page lists course information, an event schedule, course records, and information for volunteers and sponsors. Visit the organization's website for the most recent information.