The course
The Lost Sierra Endurance Race links Downieville, the Sierra Buttes, and Plumas-Eureka State Park near Graeagle over a web of alpine and mountain-bike singletrack: the famous Divide Trails, the Pacific Crest Trail, and the Lakes Basin trails. By the race's own breakdown, roughly 70 percent is alpine singletrack over rocks and roots, about 20 percent is mountain-bike singletrack, and only about 10 percent is dirt, gravel, or paved road. So know what you are signing up for. This is a runner's mountain course, not a fire-road grind.
The 100K: an out-and-back through the high country
The flagship 100K starts in downtown Downieville at 5:00 AM and climbs up toward the Sierra Buttes, then turns north toward Plumas-Eureka State Park near Blairsden and Graeagle, where the turnaround sits, before sending you back the way you came. It carries roughly 10,780 feet of climbing across nearly all singletrack, with five unique aid stations and crew access at a few of them. And because it is an out-and-back, you see every climb twice, once on the way out and once on tired legs coming home. That second pass is the crux of the whole day, in your legs and in your head.
The smart move is to climb the early divide trails and the long Lakes Basin pulls by effort, hike the steep rocky pitches instead of grinding them, and save your running legs for the smoother singletrack. The high points sit well above 7,000 feet, so the air is already thinner than most of us train in, and a given grade is going to feel harder than it does back home.
The 50K and 25K: shorter, still steep
The 50K is a point-to-point from Plumas-Eureka State Park down to Downieville, about 5,360 feet of gain on nearly all singletrack, with two big climbs early at roughly miles 2 and 8. On paper it runs downhill to the finish, but those early climbs and the technical alpine footing keep it honest. The 25K is a canyon loop out of Downieville on the First, Second, and Third Divide Trails, about 2,330 feet of gain, mostly singletrack with a little gravel and no single giant climb, just constant rolling vertical on classic Lost Sierra trail.
Whichever distance you pick, the surface is the story. Rocky, rooty, technical alpine singletrack rewards sure feet and strong quads way more than raw flat speed. So practice running technical descents when you are already tired, because that is exactly what the back half of every distance here is going to ask of you.
Heat, altitude, and where time gets lost
This is a July race in the Sierra Nevada. Down in the Downieville canyons, midday highs commonly run into the 80s Fahrenheit, while the high country stays cooler and breezier, so you move through real temperature swings over one day. July is also the driest month up here, so snow is not a factor and the trails are usually dry and dusty. But the sun is strong, and the exposed midday miles are where dehydration and overheating quietly cost people time.
Time gets lost three ways on this course. Going out too hard on the early climbs while the altitude is still biting you. Trashing your quads on the technical descents so the trip home or the last canyon miles turn into a survival shuffle. And falling behind on fluid and sodium during the hot middle hours. Stay on top of all three and you protect a strong finish.
Aid stations and cutoffs
The 100K is supported by five unique aid stations across the out-and-back, with crew access at a few of them and intermediate cutoffs along the way. The 50K uses a smaller set of stations and the 25K has a formal aid station plus a water stop. Published overall limits are roughly 20 hours for the 100K, about 10 hours for the 50K, and about 6 hours for the 25K.
The terrain is slow, so those cutoffs bite harder than the raw distances make them look. And the 100K intermediate cutoffs mean you cannot just hike the first half and expect to claw the time back later. Check the official cutoff chart for the current edition and build your pacing plan backward from each aid station with a buffer.
Pacing strategy for the Lost Sierra
A climbing-heavy, technical, moderate-altitude trail race rewards patience and sure feet. Pace this course by effort and by grade, not by the flat-ground numbers off your home training runs.
Pace the climbs by grade, not by clock
On a 100K with nearly 11,000 feet of gain, your moving pace is going to swing all over the place between the steep singletrack climbs and the runnable sections, and that is fine. That is what you want. Power-hike the steep rocky pitches and run the smoother grades. Trying to hold one minutes-per-mile number across this terrain is the fast way to cook the early climbs and have nothing left for the trip home.
Use our free grade-adjusted pace calculator to turn your flat fitness into honest effort targets for the steep Lost Sierra climbs, so you actually know whether you are pacing the vertical you can hold or burning matches you are going to need late in the day.
Protect your quads for the technical descents
The descents here are rocky, rooty, and relentless, and they are where quads go to die. Hold back early, run the downhills light and under control instead of bombing them, and your back half is going to be a whole lot better. On the 100K out-and-back especially, the climbs you fly down on the way out are the same ground you have to manage on tired legs coming home.
To set a finish goal that actually accounts for all that vertical, use our vert-aware race time calculator. It factors the climbing into your projected finish, so you are not stuck on some flat-course estimate that the Sierra Buttes is going to quietly tear apart.
Respect the altitude and the heat window
With high points well above 7,000 feet, the early climbs are going to feel harder than the same grade at sea level, so pace the high sections easy by breathing and effort. Then plan for the heat window. As you drop into the warmer canyon miles in the middle of the day, keep your pace honest and disciplined, and as the afternoon cools off you can open it back up. But only if you stayed on top of your fluid and your fuel through the hot stretch.
If you want to know how your fitness from a recent race carries over to a technical mountain 100K, 50K, or 25K like this one, our race equivalent calculator helps you reality-check your goal before you lock in a finish time.
Fueling strategy for the Lost Sierra
A long day on technical trail with warm midday sun makes your fueling and hydration matter as much as your fitness. The heat in the canyons is the thing that wrecks otherwise well-trained runners, so plan for it.
Carbs: ramp to the high end, on a trained gut
For an effort this long, aim for 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 a single sugar lets you, and rehearse your exact hourly carb number on long technical training runs so 80 to 90 g/h feels normal, not like an experiment, by race day.
The heat makes all of this harder, because a hot stomach takes in less. That is one more reason to practice fueling when it is warm out and to keep eating through the ugly canyon miles, the stretch where your appetite drops off but your engine still needs the fuel.
Sodium and fluid: built for the heat and the long gaps
On the warm, exposed midday miles your sweat losses can run high, so bias your sodium toward 500 to 700 mg per liter of fluid. The alpine singletrack between aid stations is slow, so carry enough fluid and calories to cover those long gaps instead of running dry waiting on the next stop. Cramping, a sloshy stomach, that wrung-out feeling late in the race, those are almost always fluid and sodium problems, not fitness problems.
Dial in a plan with our free ultra fueling calculator. Put in your weight, your goal time, and the heat you expect, and it gives you a carb, sodium, fluid, and caffeine number per hour built for the Lost Sierra duration and conditions. Then go test it in training, do not save it for race day.
This guide is for planning and training, and it reflects publicly available information about the Lost Sierra Endurance Race. Race details, the date, course, aid stations, and cutoffs, can change year to year, and the 2027 edition had not been formally dated when this was written. So always confirm the current specifics on the official Bad Luck Run Club race website before you train or travel.