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⏵ Course guide · Montana ultra

The Rut 50K Course Guide

The Rut 50K is a skyrunning monster at Big Sky, Montana, built around the climb to the 11,166-foot summit of Lone Peak with something like 10,500 feet of vertical packed into 31 miles. It has a reputation as one of the most brutal 50Ks in the country, and the talus, the exposure, and the altitude all earn it. I will walk you through the course first, then give you a pacing and fueling plan that fits the climbing and the thin air. There are free calculators along the way to dial in your own numbers.

⏵ At a glance

The Rut 50K quick facts

Date
Sunday, September 13, 2026 (festival runs Sep 11 to 13)
Location
Big Sky Resort, Lone Peak, Madison Range, Big Sky, Montana
Distances
50K, plus 28K, 21K, 11K, and the Lone Peak Vertical Kilometer
Elevation gain
50K: about 10,500 ft over roughly 31 miles, summiting 11,166 ft Lone Peak
Start
6:00 AM, wave starts at five-minute intervals
Aid stations
5 fully stocked plus 1 hydration-only along the 50K (Skratch Labs supplied)
Cutoff
Strictly enforced overall and intermittent checkpoint cutoffs; confirm current times with the race
Series
Skyrunner World Series event; not a Western States, UTMB, or Hardrock qualifier

These facts come from the official race site, RunSignup, and public race reports. The exact date, cutoffs, and aid stations change year to year, so confirm the current race-day details before you commit.

The course: where The Rut is won and lost

The 50K is a roughly 31-mile loop out of Big Sky Resort with about 10,500 feet of climbing, and it throws every kind of mountain terrain at you: jeep roads, forested singletrack, alpine ridgeline, and the steep rocky scramble over Lone Peak. Aid comes at five fully stocked stations plus a hydration-only stop, roughly at Moonlight near miles 6 and 12, Swiftcurrent near 19, the summit around 21, a Shedhorn water-only around 24, and Andesite near 26.5. The day really splits into the long grind up to Lone Peak and the punishing way back down.

The climb: Headwaters ridge and the haul up Lone Peak

The whole race is built around getting to the top of Lone Peak around mile 21, and the climbing up there is no joke. The Headwaters ridge ramps up at something close to 1,000 feet per mile, and the final pitch up the peak is a steep, rocky, exposed scramble where you are using your hands and watching for rockfall. This is power-hiking territory. Nobody is running the steep stuff, and trying to is how you cook yourself before the hardest part of the day.

Be patient and keep the effort honest on the way up. The altitude is real here (you are working between roughly 8,000 and 11,000-plus feet), so the same grade that feels fine at sea level will have you gasping. Manage your breathing, eat and drink on the climbs, and get to the summit with something left, because the descent is where this course actually breaks people.

The descent: steep talus that wrecks quads

Coming off Lone Peak is steep, loose, dinner-plate talus, and it demands total focus. This is not a place to bomb downhill on autopilot. One bad step on the scree and your day is over, so you pick your line, stay light, and accept that the descent off the summit is slower and more technical than the numbers suggest. Strong, controlled downhill running is a real skill here, and the people who trained it move past the people who only trained climbing.

Even after the worst of the talus, the back half keeps taking from your legs on rocky singletrack, and there is one last roughly 600-foot climb late in the race that feels like it will never quit. If your quads are trashed from the descent or you went out too hard, those final miles to the finish at Big Sky turn into a grim shuffle.

Altitude, exposure, and mountain weather

This is a high alpine course, so the weather can be anything. Early September at Big Sky can serve up highs in the 80s or warmer down in the valley and lows in the 50s, but up on the ridge and the summit you can hit wind, cold, and even snow, and some years wildfire smoke hangs over the whole thing. Pack for both ends of that. A lot of finishers carry a light layer and gloves for the top even when it is warm at the start.

The exposure up high is the other thing to respect. The Headwaters ridge and the Lone Peak ascent and descent are steep and technical with real fall and rockfall hazard, so this is a course where your footing and your head matter as much as your fitness. Treat the high section with respect and you will get through it; treat it casually and the mountain will remind you where you are.

Pacing strategy for a 10,500-foot skyrunning 50K

With this much vert and this much technical terrain at altitude, The Rut is about managing effort, not chasing a pace chart. Your flat-ground splits are useless up here. Run the climbs by feel and save your legs for the descent and that last cruel climb.

Pace the climbs by grade and effort, not the watch

On grades near 1,000 feet per mile, your mile pace is meaningless and you should not even look at it. What matters is a steady, sustainable effort you can hold up the grade while still being able to eat and breathe, and that means hiking the steep pitches without guilt. The classic Rut blow-up is pushing the early climbs because you feel strong, then having nothing for Lone Peak and the descent. Use a grade-adjusted pace to turn your real fitness into honest climbing and descending targets so you do not torch the first half.

Build a vert-aware finish prediction

Do not even think about predicting your Rut time off a road 50K. The 10,500 feet of climbing, the talus descent, the altitude, and the technical footing add hours, which is why median finishes sit near 10 hours instead of the 5 or 6 a flat 50K might take. A vert-aware finish prediction that accounts for this course’s climbing gives you a realistic window and lets you work backward into the checkpoint cutoffs, so you actually know how much margin you have at Lone Peak instead of guessing.

⏵ Free tools to pace this course

Fueling strategy for altitude and a long day

Most runners are out on The Rut 50K for somewhere around 7 to 10-plus hours, much of it climbing at altitude where your gut does not want to cooperate. That makes carbohydrate, sodium, and fluid every bit as important as your fitness.

Carbs: steady, simple, and altitude-tested

For a 7 to 10-plus hour effort, aim for roughly 60 to 90 grams of carbohydrate per hour, and be willing to sit at the lower end if the altitude shuts your stomach down. Thin air kills appetite and slows digestion, so keep your fuel steady and easy to get down rather than gambling on big doses late when you feel rough. Practice your exact race-day carb plan on long climbs, ideally at elevation if you can get there, so taking in fuel while power hiking up a steep grade feels routine instead of like a science experiment.

Sodium and fluid: cover the long climbs between aid

Aid is spaced for a mountain course, with long climbs between stops, so carry enough fluid and salt to get yourself across the gaps instead of rationing to the next station and arriving empty. If the valley is warm you will sweat more than the cool summit air makes you expect, so lean toward the higher end on sodium, often around 500 to 700 milligrams per liter, and more if you are a heavy or salty sweater. Weigh yourself before and after a hot or high long run to find your real sweat rate, then build your plan around your own number.

⏵ Build your fueling plan

Get a carb, sodium, fluid, and caffeine plan per hour built for your weight, your goal time, and the Rut’s altitude and long climbs with the free ultra fueling calculator. Browse the rest of the free running tools at the tools hub.

⏵ Train for it with Summit Line

Get a race-day plan built around YOUR fitness, this exact Rut course profile, and your projected splits. Summit Line reads your real training, builds a plan for all that vertical, and rehearses your fueling so race day on Lone Peak is something you execute, not guess at.

Start free →Explore the demo

The Rut 50K FAQ

How hard is The Rut 50K?

The Rut 50K is one of the hardest 50Ks in the country, full stop. You climb about 10,500 feet over roughly 31 miles and tag the 11,166-foot summit of Lone Peak around mile 21, with steep talus, loose rock, and real exposure up high. It is a true skyrunning course, not a runnable forest 50K, so a lot of the day is power hiking up grades close to 1,000 feet per mile and picking your way down dinner-plate scree. Median finish times sit close to 10 hours, which tells you everything about how much vert and technical terrain it packs in.

How much climbing is in The Rut 50K?

About 10,500 feet of vertical gain over the roughly 31-mile course, with a matching amount of descent. The biggest single piece is the Headwaters ridge climb followed by the haul up Lone Peak, where the grade gets close to 1,000 feet per mile near the summit. After the top you give almost all of it back on steep, loose talus, then there is one last cruel little 600-foot climb late in the race that feels like it will never end.

How should I fuel for The Rut 50K?

Plan for a long day, often 7 to 10-plus hours, at real altitude where appetite drops and your stomach slows down. Most runners do well on roughly 60 to 90 grams of carbohydrate per hour, leaning lower if the altitude wrecks your gut and higher only if you have trained it. Sodium goes up if it is hot, and early-September days at Big Sky can climb into the 80s, so carry enough fluid and salt to cover the long climbs between aid. Run your own numbers for your weight, goal time, and the forecast with the free ultra fueling calculator.

What are the cutoff times for The Rut 50K?

The Rut publishes an overall finish cutoff plus intermittent checkpoint cutoffs along the course, and the race makes a point of saying they are strictly enforced. Because of the wave start, the clock is adjusted so later waves get the same amount of time, but you still cannot bank all your buffer for the end. The exact times shift year to year and the race posts them as part of the 50K details, so confirm the current numbers before you start. Plan to reach Lone Peak with margin, because the talus descent and that last climb eat time fast.

What is the terrain and weather like at The Rut 50K?

You cover everything: jeep roads, forested singletrack, alpine ridgelines, and the steep, rocky scramble up and off Lone Peak. The Headwaters ridge and the Lone Peak ascent and descent are extremely steep and technical with exposure and rockfall hazard, so this is a hands-on, watch-your-feet kind of course up high. Weather is pure mountain: early September can bring highs in the 80s or warmer down low and lows in the 50s, plus wind, cold, or even snow on the summit, and wildfire smoke is a real possibility some years. Dress and pack for both ends of that range.

Is The Rut 50K a good first 50K?

Honestly, no, I would not make The Rut your first 50K. The altitude, the 10,500 feet of climbing, the technical talus, the exposure, and the strict cutoffs all stack up into a race that punishes anyone who has not prepared for steep mountain terrain. If you already have ultra experience and you specifically train the climbs, the descents, and time on technical rock at elevation, it is an incredible goal race. The 28K or 21K is the smarter way to taste the Rut before you commit to the full 50K.

This guide is independent and for planning only. The course details, dates, cutoffs, and aid stations come from public sources and can change year to year, so confirm the current specifics with the official race before you register or run. The fueling and pacing advice is general and not medical advice.