Blue Sky Trail Marathon & Half Marathon

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4780 W County Rd 38e, Fort Collins CO

Saturday, October 17th, 2026

Blue Sky Trail Marathon & Half Marathon

Welcome to the Blue Sky Trail Marathon & Half, Fort Collins's original and only trail marathon.

Taking place on the trails between Horsetooth Mountain Park and the Devil's Backbone Open Space, the course takes you on a north-south tour of the easternmost hogbacks of Northern Colorado's mighty Front Range.

The marathon boasts 3,500 feet of elevation gain/loss, while the half marathon checks in at 1,800 feet, and the route offers a little bit of something for everyone. It is designed to appeal to both veteran trail runners and those looking to experience their first trail racing adventure. The generous nine hour cut-off should ensure a successful day for everyone.

The course is 100% dirt and 90% sweet Colorado singletrack. The terrain ranges in difficulty from smooth dirt trail to technical rock gardens. A small portion of the route is on smooth dirt road (no motor vehicle access) and gravel bike path, with the meat of the running done on the beautiful and distinctive redstone hardpack of the Blue Sky Trail.

After the race, kick back and enjoy the always-popular barbecue and generous sponsor giveaways.

Race Details

Start: Blue Sky Trailhead, Horsetooth Mountain Park, Fort Collins, Colorado
Distance: 26.7 miles (3,500') or 13.4 miles (1,800')
Min/Max Elevation: 5,300'-6,500'
Average Elevation: 5,700' Marathon

Terrain: Marathon: 22mi dirt singletrack, 3mi rocky singletrack, 2mi dirt road: Half Marathon: 13.0mi dirt singletrack, 0.5mi dirt road
Fauna: Deer, abert squirrel, golden eagle
Registration Cap: 400 Marathon / 400 Half
Time Allowance: 9 hours Marathon / 6 hours Half Marathon

Event Dates

Marathon: Oct 17, 2026
Half Marathon: Oct 18, 2026

Registration

Fees for the 2026 Blue Sky Marathon & Half Marathon are as follows:

Marathon Fees

Dec 15 – Feb 28: $110 + $7.60 fee
March 1– June 30: $120 + $8.20 fee
July 1 – Oct 17: $130 + $8.80 fee
Packet Pickup: $145

Half Marathon Fees

Dec 15 – Feb 28: $90 + $6.40 fee
March 1– June 30: $100 + $7.00 fee
July 1 – Oct 17: $110 + $7.60 fee

What You Get in Return for Your Registration Fee:

A beautiful, challenging and well-marked course on some of the best trails in Fort Collins
Enthusiastic, knowledgeable race and aid station volunteers
Fully stocked aid stations
Free entry to Larimer County Open Space for the day
Generous Cut-Offs (Marathon: 9hrs / Half 6hrs)
Gender specific race T-shirt
Unique finisher award and overall and age group awards
Finish line meal with vegetarian, vegan, gluten-free and non-alcoholic options available
Professional medical and emergency communications

Waiting List

In the event that the race sells out, we will maintain a waiting list and transfer runners from the waiting list to the race roster should other runners already registered not be able to attend.

Transfer Credit Policy

If you are not able to race, we will be able to offer a race transfer credit that can be applied to any future Gnar Runners race (valid for 12 months). Credit deadlines are as follows:

Until March 31: 100% credit of registration (excluding RunSignup fees)
April 1 - July 31: 75% credit of registration (excluding RunSignup fees)
August 1 - October 15: 50% credit of registration (excluding RunSignup fees)

In order to receive your credit, you must cancel your registration through the RunSignup registration platform.

Course & Aid Stations

Course Maps

Elevation Profiles

Aid Station Information

All aid stations will offer Gnarly Nutrition Fuel2O sports drink, Hammer Gels, water and soda plus a variety of salty and sweet bites, and a selection of fruit.

*There will be GF/Vegan alternatives for nearly all non-GF/V standard offerings. These are typically held back to save them for those who need them, so please ASK!