THE RUT 21K RACE

Friday, September 12, 2025 | 11:00 AM Start

The Rut 21K is the perfect addition to our series of races as it fills the very large gap between our 11K & 28K race experiences. For the Rut Runner looking to level up from the 11K, but is not quite ready for the 28K, or who simply wants to run a beautiful and challenging course on the flanks of Lone Peak, this race is for you. While this race still has a lot of climbing and descent (approx. 4000 ft) it does not traverse the exposed and rugged ridgelines of lone peak like the Rut 28K and 50K. Instead, this course utilizes many of Big Sky’s best single-track trails creating one big loop that plays along the border of the subalpine and alpine areas of the mountain.

21K Map

Aid Stations & Cut-off Times (We are a cupless event)

There are 3 fully stocked aid stations along the 21K course. Each aid station will be supplied with water, Skratch Labs goodies, sweet and salty snacks, first aid, and energetic volunteers!

Challenger: (Mile 2.85) (Cut off time of 1:25PM)
Swiftcurrent: (Mile 5.65) (Cut off time of 2:40 PM)
Andesite: (Mile 9.25) (Cut off time of 3:55 PM)
Finish Line: (Mile 13.4) (Cut off time of 5:25 PM)

*Cut-off times will be strictly enforced for the safety of the runners and the volunteers. Cutoff times are the same regardless of your wave start time. Also, time has been added to cutoffs as the event has grown and waves have been added. While it is true that those in wave one have more time, we have added time to all the cutoffs with the later wave starts in mind. This is the best option forward as it is of the utmost important for the on trail experience to allow those who have faster estimated times to begin first to limit the amount of passing on the trail. Thank you in advance for helping us limit congestion on the trails!

Skratch Labs products you can expect on the course:

Anytime Energy Bars:

Peanut Butter + Chocolate Chip (new flavor!)
Cherries & Pistachios

Sport Energy Chews

Raspberry
Orange

Sport Hydration Mix

Lemon & Lime
Strawberry Lemonade

By the Numbers

13.2 Miles | 21.2 Kilometers
4100 ft. | 1250 Meters of elevation gain
Low Point: 7,500 ft | 2286 Meters
High Point: 9,801 | 2988 Meters
3 Aid Stations
1 day of making great memories in the mountains!

ADDITIONAL INFORMATION

PRIZES

All 21K finishers will receive a unique finishers award.
Age group awards for age groups (Under 20, 20-29,30-39, 40-49, 50-59, 60-69, 70+)
Podium ceremony with awards designed by a local artist for our top five overall men, women, and non-binary athletes.

WAVE STARTS

To limit congestion on the course, the 21K will have 8 wave starts separated by five minutes each. When participants sign up they share an estimated finishing time for their event. We then assign waves based on their estimated finishing time. We will send an email out to runners with their assigned wave. Also, runners’ waves will be on the back of their bib. Runners must start in their assigned wave.

*Cut-off times will be strictly enforced for the safety of the runners and the volunteers. Cutoff times are the same regardless of your wave start time. Also, time has been added to cutoffs as the event has grown and waves have been added. While it is true that those in wave one have more time, we have based out cutoffs on the start time of the final wave. This is the best option forward as it is of the utmost important for the on trail experience to allow those who have faster estimated times to begin first to limit the amount of passing on the trail. Thank you in advance for helping us limit congestion on the trails!

Crewing/Spectating

Crewing of runners is not allowed. You are, however, highly encouraged to get out on the course and see your runners as much as possible and cheer for them! Learn more about spectating opportunities on our spectator page.

21K Course Markings (Pink Pin Flags)

This is not an orienteering race. The race organizers will do everything they can to have the course marked well for race participants on the day of the event. Runners must stay on the trail. No switchback cutting! The 21K will be marked with pink pin flags.

Course Reconnaissance

We welcome you to check out the Rut course prior to the event, but please be aware that you cannot go on downhill mountain biking trails other than on race day. It is unsafe to do so. Please check out Big Sky Resorts’ summer trails map to see what trails allow running and hiking before heading up to the resort.

Weather

Please be prepared for any type of weather. Though weather in Big Sky is relatively mild and stable in mid-September historically, we are still in the mountains and conditions can quickly change. This is a challenging run on challenging terrain and the race organizers reserve the right to stop the race at any time, should they deem the course unsafe due to weather.

Rut Policies & Rules

Learn more about all Rut Policies and Rules HERE

Rut Registration Policy

There will be no deferrals, transfers to other runners, or waitlists for any Rut race. No exceptions.
Distance Transfer - Our hope is for you to make it to a Rut starting line, even if it's not the one you originally intended. With this in mind Rut runers may move down in distance for certain events. We do not allow transfers into the VK. The 50K can transfer to the 28K, 21K, or 11K, but not the VK. The 28K can transfer to the 21K, or 11K, but not the 50K or VK. The 21K can transfer to the 11K, but not the 50K, 28K, or VK. The VK can transfer to the 11K only. The 11K cannot transfer to another event. Transfers must be completed no later than August 15th. A transfer in distance will be charged a $5 processing fee.
Pregnancy Policy - If you become pregnant, or adopt a child, after registering for a Rut race and cannot participate, you can use your race entry for up to 2 years after the original race date. To take advantage of this policy, you must contact the Rut Registration Director (registration@runtherut.com) by race weekend. Requests made after race weekend will not be honored.
Registration Cancellation Policy - If you need to cancel your race entry, we are happy to offer partial credit toward the following year's Rut. This helps us to balance the needs of our participants with the time and nonrecoverable expenses incurred in organizing our event. Credits are awarded based on the following tiered structure by date.
- Cancel by 11:59 PM on June 15th: 60% credit to the following year's Rut (e.g. If you spend $100 on a race this year, and decide to cancel, you will have $60 to go towards the following year's race registration for whatever distance you choose.)
- Cancel by 11:59 PM on August 15th : 40% credit to the following year's Rut (e.g. If you spend $100 on a race this year, and decide to cancel, you will have $40 to go towards the following years race registration for whatever distance you choose.)
How to Cancel Your Registration - To receive credit, runners must cancel their registration through their Runsignup account. Credits cannot be applied retroactively, and cancellations must be completed by the runner themselves.
- Important Details About Race Credit
  - Credits can only be used for the following year.
  - To ensure those with credits can enter into the following year's race, we will have a priority registration window available prior to registration opening to the public.
  - Once the event fills the credit can no longer be used.

Questions? Check out our Rut Registration FAQ's page.