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Mammoth Trail Fest Course Guide
Mammoth Trail Fest is a high-altitude alpine party in the Eastern Sierra above Mammoth Lakes, with an 82K, a 50K, and a 26K that all run mostly between 8,000 and 11,000 feet and summit Mammoth Mountain. You get fast, flowing singletrack, real climbing, soft pumice, and thin air the whole way. I will walk you through the course, and then give you the pacing and fueling that actually works for those conditions, plus some free tools to dial in your own numbers.
The course
Every Mammoth Trail Fest distance is a single loop on its own unique trail, no out-and-backs and no repeated sections, and it stitches together smooth alpine singletrack, rocky technical pitches, soft pumice, and short bits of bike path and access road. The terrain is built for flow more than constant scrambling. But it all sits high. The 50K averages above 9,100 feet, and every distance tops out by summiting Mammoth Mountain at 11,053 feet, usually by way of the Dragon’s Back. The altitude is what gets you here, not the technical stuff.
The altitude sets the tone
There is no easing into the thin air here. You start high and you stay high. The 50K averages above 9,100 feet and the whole field spends the day between roughly 8,000 and 11,053 feet, and all that time up high caps what you have got. Your top effort is lower than it is at home, the climbs feel harder than their grade, and you recover slower between them. If you are coming from sea level, expect to pay a tax all day, not just on the steep stuff.
So treat the altitude like a pacing rule from your very first step. Run the high sections by breathing and effort, not by the pace numbers you are used to, and do not get greedy banking time early. That runnable, fast-feeling singletrack will tempt you into pushing. Push too hard up high and you will spend the back half gasping.
Climbing, pumice, and the Dragon’s Back
The gain stacks up across alpine singletrack and soft volcanic pumice instead of one huge wall. The pumice is its own thing. It is soft and it saps your energy underfoot, so good footwork and a little patience go a long way on those sections. The signature feature on more than one of the courses is the Dragon’s Back, the high, exposed ridgeline approach that drops you onto the summit of Mammoth Mountain at 11,053 feet with huge Eastern Sierra views and the thinnest air of the day.
The 26K packs about 3,900 feet of gain into 16.1 miles, the 50K nearly 7,000 feet across about 32 miles, and the 82K roughly 13,400 feet over about 51 miles. Whichever one you run, the climbing keeps coming but it has a rhythm to it. Power-hike the steep pitches with purpose and run the gentle grades, and that is how you keep moving without redlining up high.
Where the race is won or lost
This course rewards an honest, even effort way more than raw speed. The people who fall apart are almost always the ones who treated the early runnable singletrack like a road race and went into oxygen debt up high, or the ones who quietly under-ate and under-drank in the dry mountain air and bonked late. Be patient on the climbs and stay on top of your fuel and fluid through the high middle miles, and that is the difference between a strong finish and a long slog.
The summit push and the descents off the high country are the other thing that decides your day. Coming down from 11,053 feet on pumice and rocky singletrack with tired legs is a quad-management problem, and the people who held back on the early descents still have working legs for the final miles. Save something for the way down.
Aid stations and cutoffs
The races are well supported for how long they are. The 50K has six fully stocked aid stations and the 26K has four, with water, sweet and salty snacks, fruit, GU products, and even summit pancakes up top. The 50K runs a generous 12-hour cutoff (96 percent finished in 2025) and the 26K a 7-hour cutoff (97 percent finished).
The 82K is the big ultra here, and its aid layout and cutoff change from year to year, so confirm the official 82K checkpoint and cutoff details before you plan anything. The altitude can slow you down more than you expect late in the day, so build your pacing backward from the cutoffs and give yourself a buffer. And carry enough fluid and calories to cover the high, dry stretches between aid.
Pacing strategy for Mammoth Trail Fest
A high, climbing-heavy alpine course rewards holding back and punishes your ego. Pace this race by effort and by grade, and respect the altitude from the first mile, not just on the steepest climbs.
Pace the climbs by grade, not by clock
With thousands of feet of gain spread across the loop, your moving pace is going to swing all over the place between the runnable singletrack and the steep pitches, and that is exactly how it should be. Power-hike the steep climbs and run the gentle grades. Trying to hold one steady minutes-per-mile number across this terrain, at this altitude, is a quick way to cook the climbs and blow up high on the mountain.
Use our free grade-adjusted pace calculator to turn your flat fitness into honest effort targets for the steep Mammoth climbs, so you know whether you are pacing the vertical in a way you can hold or burning matches you are going to want later on the Dragon’s Back.
Respect the altitude all day
Because the whole course lives between roughly 8,000 and 11,053 feet, the altitude tax never lets up. Run the high sections easy, by breathing and effort, and just accept that your numbers are going to look slower than they do at home. That is the mountain, not your fitness. If you can, get there a few days early to start adjusting, or build some altitude or hard-climbing work into your training block.
To set a finish goal that actually accounts for all that vert, use our vert-aware race time calculator. It works the climbing into your projected finish so you are not stuck on a flat-course estimate that the Eastern Sierra is going to quietly tear apart.
Bank the runnable miles, protect your legs
The pacing shape you want here is even to slightly negative on effort. Stay controlled on the early runnable singletrack so you are not in oxygen debt up high, then keep moving steadily through the climbs and the summit. Hold back on the early descents off the high country so your quads still have something left in the pumice and rock for the final miles.
If you want to know how your fitness from a recent race carries over to a high-altitude trail effort like this, our race equivalent calculator helps you reality-check your goal before you lock in a finish time.
Fueling strategy for Mammoth Trail Fest
Up at altitude, fueling and hydration matter just as much as fitness. Thin, dry mountain air kills your appetite and pulls more water out of you, so the people who eat and drink on a schedule are the ones still moving well late in the day.
Carbs: keep eating even when the air kills your appetite
For something this long, go after roughly 60 to 90 grams of carbohydrate per hour, leaning toward the high end once your gut can handle it. Use a glucose-plus-fructose blend so you can absorb more than one sugar alone lets you, and practice your exact hourly carb number on long climbs at effort so it feels normal by race day.
The altitude is the trap. Thin air kills your appetite and a working stomach can take less than usual, so it is easy to quietly under-fuel up high and bonk on the back half. Set hourly reminders, keep easy-to-swallow carbs handy for when solid food stops sounding good, and lean on the aid stations, including those summit pancakes, to top up.
Sodium and fluid: built for thin, dry air
Mountain air is dry, and up high you lose more water just from breathing than you would think, on top of what you sweat, so do not let the cooler temperatures trick you into under-drinking. Keep your sodium somewhere around 400 to 700 mg per liter of fluid, and carry enough to cover the high, dry gaps between aid stations. Cramping, a sloshy stomach, and that wrung-out late-race feeling are usually fluid and sodium problems, not fitness problems.
Dial in a personalized plan with our free ultra fueling calculator. Enter your weight, your goal time, and your distance, and it gives you a carb, sodium, fluid, and caffeine plan per hour built for the Mammoth Trail Fest length and altitude. Then go test it in training.
This guide is for planning and training purposes and reflects publicly available information about Mammoth Trail Fest. Race details, including the dates, distances, course, aid stations, cutoffs, and qualifier status, can change year to year. Always confirm the current specifics on the official Mammoth Trail Fest race website before you train or travel.