Ultramarathons in Colorado
Colorado has 4 upcoming ultramarathons scheduled for 2026: Hardrock 100 in Silverton on July 15, Leadville Trail 100 Run in Leadville on August 15, Run Rabbit Run in Steamboat Springs on September 15, and NoCo Urban Ultra & Relay in Bellvue on April 11.
Showing all 4
Ultra
Leadville Trail 100 Run
Leadville, CO
Ultra
Leadville Trail 100 Run
August 15, 2026
Leadville, CO
Ultra
Run Rabbit Run
Steamboat Springs, CO
Ultra
Run Rabbit Run
September 15, 2026
Steamboat Springs, CO
Frequently asked questions
What is an ultramarathon?▾
An ultramarathon is any race longer than the standard marathon distance of 26.2 miles. Common ultra distances are 50K (31 miles), 50 miles, 100K (62 miles), and 100 miles. Most ultras take place on trails.
What are the most famous ultramarathons in the US?▾
Western States 100 is the most prestigious, followed by Leadville Trail 100, Hardrock 100, and UTMB Canyons. The JFK 50 Mile is the oldest US ultra, running since 1963. Find all of these on RACE.
How do I train for my first ultra?▾
Most runners build up to their first 50K after completing a marathon. Training typically spans 16-24 weeks with weekly mileage of 40-60 miles, including back-to-back long runs on weekends to simulate race-day fatigue.
Do I need trail experience for an ultramarathon?▾
While many ultras are on trails, some are on roads or mixed terrain. For trail ultras, practice running on uneven surfaces and hills. A 50K on a relatively flat trail is a great first ultra for road runners making the transition.