Butte 100 MTB Race

The Butte 100

Three mountain bike races on the Continental Divide just outside Butte, Montana: the Butte 100, the Butte 50 and the Sorini 25, each with a tandem division. The 100-mile race climbs more than 16,000 feet.

The race has grown from a small group of dedicated locals on a gravel road to world-class athletes on world-class trails, with the USFS, BLM, the community of Butte, our sponsors and the “neon army” of volunteers behind it.

Saturday, July 17, 2027 • Homestake Pass

Registration opens Sunday, December 6, 2026 at 12:00 pm MST. Early-bird pricing runs through Wednesday, December 9 at 11:59 pm MST.

Register: early bird Dec 6–9

Pick your distance

Saturday, July 17, 2027 at Homestake Pass. Butte 100 starts at 6:00 am, Butte 50 at 7:00 am and Sorini 25 at 9:00 am MDT. Each distance has a solo and a tandem division.

Butte 100

$100

6:00AM MDT

Events: Butte 100 Tandem 100

Butte 50

$135

7:00AM MDT

Events: Butte 50 Tandem 50

Sorini 25

$100

9:00AM MDT

Events: Sorini 25 Tandem 25

Race day

A Butte 100 racer in a red jersey rides a singletrack trail through a mountain meadow, with forested ridges behind. Photo credit: Doug Tate.

Start times, Saturday, July 17, 2027

6:00 am Butte 100 • 7:00 am Butte 50 • 9:00 am Sorini 25 (MDT)

The courses

The Butte 100 climbs more than 16,000 feet, the Butte 50 more than 8,500 feet and the Sorini 25 about 4,000 feet, on the Continental Divide outside Butte.

Come prepared

These are unsupported wilderness races. Aid stations stock water, Hammer Nutrition, Pickle Juice and some fruit; pack drop bags for everything else. Aid-station cutoff times are final.

Aid stations

Race rules

Race Bible

Follow it live

Download the free Competitive Timing app to follow the Butte 100 on race day. Let your family and friends know so they can track you during the race.

Live results Download for iPhone Download for Android

Racer FAQs

100-mile race is 104.4 miles and over 16,000 feet (ft.) of climbing.
50-mile race is 54.6 miles and over 8,500 ft. of climbing.
Sorini 25 is 29 miles and around 4,000 ft. of climbing.

Cutoff Times are final. If you do not make it to the aid stations by these times, you will not be allowed to continue. These are set to ensure your safe completion of the race and to be respectful of the volunteers, including aid station volunteers and search and rescue. NO EXCEPTIONS. ANY RIDER BEING ABUSIVE TO A VOLUNTEER(S) FOR MISSING THEIR CUTOFF TIME WILL NOT BE ALLOWED TO RACE AT THE BUTTE 100/SORINI 25 IN THE FUTURE.

Butte 100 cutoffs:

Aid Station 5: 2:00:00 p.m.
Aid Station 8: 6:00:00 p.m.
Aid Station 9: 7:30:00 p.m. without a light, or 8:00:00 p.m. with a light. A sufficiently bright bikelight is required to ride at night after 7:30 p.m. to pass Aid Station 9. If you are unsure if you can make the 7:30 p.m. cutoff time, please feel free to bring a flashlight.

Butte 50 cutoffs:

Aid Station 3: 5:00:00 p.m.
Aid Station 4: 7:00:00 p.m.

If you do not make the cut-off, you are no longer a part of the race and a ride back to the start/finish will be arranged. If you make the decision to proceed: You assume your own responsibility. You are no longer covered under the Butte 100 umbrella and must find your own ride back to the start/finish line if you take this risk and proceed. If you need a rescue, you will need to call Search and Rescue and assume any associated liabilities and/or costs.

All Aid stations will have water for riders and will be double stocked (for the two laps) with HAMMER NUTRITION, Coca-Cola (aid station 2,3,7,8), Pickle Juice, and some fruit.

In addition, two new water stations will be located between Aid Stations 2 and 3 (at the top of Basin Creek climb) and Aid Stations 7 and 8 (where the CDT crosses Lime Kiln Road). These new water stations will only include water.

Nutrition, Pickle Juice--we will have some at some of the aid-stations. Electrolytes, Solid foods (energy bars, waffles, etc.)

Bike maintenance items: Chain Lube, Tube, CO2 cartridges, etc.

Comfort items: Sunscreen, Fresh socks and/or shorts, Chamois cream, Sunglass wipes, Advil, other?

Please note that aid station bags will be outside in the elements and may get hot/cold/wet/etc. As such, please do not include anything that may spoil before you are able to use it (i.e., pre-mixed drinks, fruits, vegetables, etc.) unless you have placed them in an appropriate cool and/or protective container.

Decomposed granite with sandy areas in the beginning of the course and on the Basin Creek climb. After Basin Creek, the course gets rocky and technical. A good fast rolling, high volume tire is a great option. Tires similar to Maxxis Rekon, Rekon Race, Ardent, and Aspen (risking punctures). Schwalbe Nobby Nic, Wicked Will, Racing Ralph. Vittoria Aggaro, Mezcal