Fourmidable

Auburn, United States • 21 Feb 2026

FOURmidable is a challenging trail running event held in Auburn, California, set in the scenic Sierra Nevada foothills. The race offers multiple distances including a 50K, 35.5K, half marathon, and 13K, catering to a range of endurance levels. Participants experience rugged terrain and picturesque natural surroundings, making it both a physical test and an immersive outdoor adventure. The event features a unique prize structure where prize money is community-funded and matched by the organizers, with additional bonuses for breaking course records in the 50K. FOURmidable emphasizes community support and competitive spirit in a stunning trail running environment. Visit the organization's website for the most recent information.

Race information

50 km
50k
35 km
35.5k
13 mi
1/2 Marathon
13 km
13k
Visit the organization's website for the most recent information.
Trail runs nearby

Blood, Sweat & Beers is a trail running event held in Auburn, California, nestled in the scenic American River Canyon. The race offers two challenging distances: a Long Course of 10.5 miles with over 2,470 feet of elevation gain and loss, and a Short Course of 5.9 miles with approximately 860 feet o..

The Folsom 100 is an exhilarating 100-mile ultramarathon that takes place around Folsom Lake, California. Scheduled for August 1, 2025, this challenging race features a point-to-point course with a single out-and-back section. Participants have 34 hours to complete the loop, which includes stunning..

The Trail Run at Sly Park - Summer is a scenic trail running event held at the Sly Park Recreation Area in Pollock Pines, California, within the El Dorado National Forest. The race offers multiple distances including 5K, 10K, 8 Mile, Half Marathon, 17 Mile, Trail Marathon, and a 50K ultra. Courses w..

The Mammoth Bar Trail Runs, hosted by Skybreaker Racing, is a trail running event held in Auburn, California, within the Auburn State Recreation Area. Scheduled for September 7, 2025, the event features three race distances: a half marathon, 10K, and 5K. The courses traverse the single-track and dou..

The Gold Rush Growler Trail Runs take place at Granite Beach, Folsom Lake State Recreation Area in California, featuring scenic courses along the shoreline and single-track trails. The event offers two distances: a 10-mile trail run and a 5K, both with new courses for 2025. The 10-mile course includ..

The Sunset & Cider Trail Races, held in Auburn, California's scenic American River Canyon, offer three trail running distances: 50K, 13.1 miles, and 5 miles. The courses feature mostly runnable single-track trails with moderate elevation gains—3,875 ft for the 50K, 2,082 ft for the half marathon, an..