A trail event in the foothills of the Sierra Nevada, held in Auburn, California, the heartland of ultrarunning.
The 50K, 35.5K, half marathon and 13K distances start together.
As its name suggests, the climbs and descents are “FOURmidable”—a community race that creates prize money through participant donations and matching funds.
The road to your own record
Picture the course in advance and find the pace that fits you.
When the city cheers
Streets lined with cheers, runners all around. You'll be part of that scene.
The trip that follows the run
Take it slow with the finish still in you, and meet the city all over again.
FOURmidable runner reviews and race reports
Stories from those who ran it first.
From the joy of finishing to the tough moments — read what runners wrote themselves.
Race reports: 1
TrailmommaRan in 2024
“I would most definitely rather run slow, than not at all.”
The runner fueled consistently in the Formidable 50km before struggling with late mud and strong wind. After injury prevented participation the previous year, completing the 50km mattered more than the time.
We translated a short line from each public race report and summarized the experience. Finish times are as stated by the author, and past editions may differ from this year's weather and operations.
See it on video, feel it through their stories.
Preview the course and read what runners who went before you wrote.
The categories are FOURmidable 50k, FOURmidable 35k, FOURmidable 13k, and FOURmidable Half Marathon +.
The start takes place at 855 Pacific ave, Auburn, CA at 8:00 AM local time.
Organizer
Singletrack Running
Typical race-season temperature: around 9°C (48°F)
Short sleeves or light long sleeves + arm warmers
Aid stations
Aid station provided (this is a cupless event, so bring your own cup or water bottle)
Participant benefits
Not yet confirmed in the official race guide
Where and when to collect your FOURmidable race bib
To the start line, step by step.
Pick up your bib, check your wave. So on race morning, you can just run.
From the 2026 edition
Pick up your bib at the expo
Packet pickup information has not yet been announced. For small trail races, race-morning on-site pickup is common; check the registration page announcement for details.
Stations & transport near the venue
Getting to the start
No train/bus station near venue
Start/finish at Overlook Park, 855 Pacific Ave, Auburn, CA — a local park with car parking;
Your start time, fuel and bag drop. Know them ahead and the run feels easier.
FOURmidable is a trail race organized by Singletrack Running in Auburn, California,
with four events held along trails in the Sierra Nevada foothills: 50K, 35.5K, half marathon, and 13K.
Registration is available through UltraSignup and RunSignup, and a separate pre-race training program, the FOURmidable Training Program, is also offered.
Prize money is raised through participant donations, with the organizers matching 100% of donations.
The matching cap is reportedly $3,000.
Since detailed logistics such as the exact Entry fee, field limits,
and time limit times are updated for each edition, check the official registration page for the latest announcements.
Times are local to Auburn. Check the latest official information before the race.
A trip built around the race
STAY A LITTLE
MAKE IT A RUNTRIP
The race is one day, the trip can be longer.
From a hotel that makes race morning easy, to the meals and views you'll enjoy with the medal on.
Hotels near the FOURmidable start line in Auburn
Hotels that make race morning easy
6 places
Distances are straight-line from the start. Check real travel times and booking terms with each hotel.
Hotel distances are straight-line from the start. Distances and ratings for food and sights come from the place provider, and experiences are travel products in Auburn.
