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⏵ Course guide · California ultra

Folsom Lake Ultra Trail 110K Course Guide

The Folsom Lake Ultra Trail, or FLUT, is the only race that runs all the way around Folsom Lake, a roughly 68.5 mile loop (110K) from Beal’s Point in Granite Bay, and it earns you a handcrafted wooden buckle. This is not a brutal mountain race. It is long, hot, and mostly runnable, and that is exactly what makes it sneaky. I will walk you through the loop first, then give you a pacing and fueling plan built for the distance and the heat, with free tools to dial in your own numbers.

⏵ At a glance

Folsom Lake Ultra Trail 110K quick facts

Date
Typically a Saturday in mid-September (confirm the current year)
Location
Loop around Folsom Lake from Beal’s Point, Granite Bay, CA
Distances
110K solo (about 68.5 mi) and a 3-person relay (legs of about 21.5, 24.5, 22.5 mi)
Elevation gain
Roughly 6,500 to 7,500 ft (GPS readings vary widely, from about 6,200 to 9,850 ft)
Start
5:00 AM for solo and relay runners
Cutoff
20 hr 15 min overall, with intermittent aid-station cutoffs
Course
About 82% trail, 18% road; 12 aid stations (9 with crew access); cupless
Qualifier
No Western States, UTMB, or Hardrock qualifier status listed by the race

These facts come from the official race site, UltraSignup, and ITRA. The course direction flips each year, and the date, cutoffs, and aid stations can change, so confirm the current race-day details before you commit. Race logistics change year to year.

The course: a full lap of Folsom Lake

FLUT is one big loop around Folsom Lake, starting and finishing at Beal’s Point in Granite Bay, about 68.5 miles and roughly 6,500 to 7,500 feet of gain. It is about 82 percent trail and 18 percent road, a mix of single-track, fire road, and a few bridge and pavement connectors. The catch that trips people up: the race runs clockwise one year and counterclockwise the next, so the climbs, the exposed stretches, and the aid spacing all flip depending on the year. Know which direction you are running before you study the splits.

The character: runnable rollers, not big climbs

There is no single monster climb on this course, and that is the whole point. The vert is chopped up into lots of short, punchy rollers around the shoreline, the kind that are too small to walk and too frequent to ignore. That makes FLUT feel deceptively easy early, because almost everything is runnable, and runnable is exactly the trap. The people who blow up here are the ones who run every roller hard in the first 30 miles because their legs feel great, then have nothing left when the heat lands and the back half drags on.

So treat the early loop as the easy part you are not allowed to race. Hike the steeper pinches even when you could run them, keep your effort boring, and save your legs for the long middle. The terrain rewards patience way more than it rewards a fast first marathon.

The heat and the exposure through the middle

Mid-September in the Sierra foothills runs hot. A lot of the loop is open oak-grassland and exposed shoreline with very little shade, and the afternoon can climb well into the 80s or 90s. The middle third of the race, roughly the hottest hours of the day, is where most FLUT days are won or lost. This is not a course where the heat is a footnote; it is the main obstacle.

Plan for it from the gun, not when you already feel cooked. Carry enough fluid to get across the open stretches between aid, use ice and water at the stations to keep your core temperature down, and accept that you will slow in the worst of the heat. Backing off on purpose when it is hottest is faster over 68 miles than pushing through and frying yourself.

Aid, crew, and the long stretches between

FLUT has 12 aid stations around the lake, and they are good ones, stocked with water, electrolyte, potatoes, chips, candy, gels, and salt, with the later stations adding real food like soup and quesadillas. Nine of the twelve are crew-accessible, so if you have crew this is an easy race to get supported at, and it is a great place to stash a drop bag with your night kit. It is also a cupless event, so carry your own soft flask or cup.

The thing to respect is the spacing. Some of the gaps between aid are long, and out on the exposed sections in the afternoon that gap can feel a lot longer than the mileage says. Leave each station with enough fluid and calories to comfortably reach the next one, with margin. Do not ration to the next aid and show up empty in the heat.

The back half and running into the night

Because most runners are out here for 12 to 20 hours, the back half of the loop happens in fading light and, for a lot of the field, full dark. That changes the race. Your footing gets slower, the rollers feel bigger when you cannot see the top, and the temptation to walk it in gets strong once the sun is down. A headlamp (and a backup) is not optional for most people, so plan your light into a drop bag at a crew station.

This is also where the day is decided mentally. The course is runnable to the finish, which rewards anyone who paced the first 40 miles with discipline and still has legs to keep shuffling the flats and downhills in the dark. If you trashed yourself early, those last miles back to Beal’s Point turn into a long, slow walk. Keep eating, keep moving, and break the back half into aid-to-aid chunks instead of staring at the whole distance.

Pacing strategy for a long, runnable, hot 110K

FLUT is about managing effort and heat over a very long, runnable day, not chasing a pace chart. The runnable terrain makes it easy to go out too fast, so the whole game is holding back early and still being able to run the back half.

Run the rollers by effort, not by ego

On a course this runnable, your watch will happily show you a pace you cannot hold for 68 miles, especially in the first cool hours. Pace by grade-adjusted effort instead: keep a steady, conversational output on the flats and downhills, and hike the steeper rollers even when you could run them. The classic FLUT mistake is treating the easy early miles like a marathon and paying for it across the hot, long back half. A grade-adjusted pace turns your real fitness into honest targets for the rollers so you are not quietly redlining while it still feels easy.

Build a finish prediction you can plan the cutoffs against

Do not guess your FLUT finish off a road time. The 68.5 mile distance, the rolling vert, the heat, and the night running all add real time, and the spread between a smart day and a blown-up day here is hours, not minutes. A vert-aware finish prediction that accounts for this course gives you a realistic window, and then you can work back into the intermittent cutoffs and the 20:15 overall limit, so you actually know how much buffer you have at each aid station instead of hoping.

⏵ Free tools to pace this course

Fueling strategy for the heat and the distance

Most runners are out on the FLUT 110K for somewhere between 11 and 20 hours, much of it in September heat with long exposed stretches. That makes carbohydrate, sodium, and fluid every bit as important as fitness.

Carbs: steady, trained, and all day long

For an effort this long, aim for around 60 to 90 grams of carbohydrate per hour, and only push the higher end if your gut is trained for it. The hard part on a 68 mile day is not the math, it is keeping it up hour after hour while the heat kills your appetite. Use a glucose-plus-fructose blend so you can absorb more, keep your intake steady and easy to get down, and lean on the aid-station real food (potatoes, soup, quesadillas) when gels start to turn your stomach. Rehearse your exact hourly carb number on hot long runs so 80-plus grams an hour feels normal, not like an experiment.

Sodium and fluid: built for the September heat

In the heat, bias your sodium toward the high end, often around 500 to 700 milligrams per liter of fluid, and more if you are a heavy or salty sweater. Just as important on this course, carry enough fluid to get across the long, exposed gaps between aid stations instead of rationing and showing up empty. Cramping, a sloshy stomach, and that hollow wrung-out feeling late are usually fluid and sodium problems, not fitness problems. Weigh yourself before and after a hot long run to find your real sweat rate, then build the 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 Folsom Lake heat 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 Folsom Lake loop, and your projected splits. Summit Line reads your real training, builds a plan for the distance and the heat, and rehearses your fueling so race day is something you execute, not guess at.

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Folsom Lake Ultra Trail 110K FAQ

How hard is the Folsom Lake Ultra Trail 110K?

FLUT is a long day, but it is not a savage mountain race. It runs about 68.5 miles all the way around Folsom Lake with somewhere around 6,500 to 7,500 feet of climbing, mostly on rolling, runnable single-track and fire road in the Sierra foothills. There is not one giant climb that breaks you; instead it is the sheer length, the September heat, and the fact that almost all of it is runnable that decides your day. The overall cutoff is 20 hours 15 minutes with intermittent cutoffs along the way, so a mid-pack runner has room to finish, but you have to keep moving and stay on top of heat and fuel. Plenty of people are still out there after dark, so plan for the night too.

How much climbing is in the Folsom Lake Ultra Trail 110K?

Call it roughly 6,500 to 7,500 feet of total gain over the 68.5 mile loop, though GPS watches on this course report all over the place, anywhere from about 6,200 to 9,850 feet. The point is that the vert is spread out in lots of short, punchy rollers around the lake rather than stacked into a couple of big climbs. ITRA lists the route at around 2,050 meters of gain (about 6,725 feet), which lines up with the lower end of those watch readings. The honest takeaway: this is a runnable course, and the climbs are not what get you, the distance and the heat are.

How should I fuel for the Folsom Lake Ultra Trail 110K?

Treat it as a long, hot, 11 to 20 hour effort, even if you are fast, because September around Folsom Lake gets warm and a lot of the loop is exposed. Most runners do well on roughly 60 to 90 grams of carbohydrate per hour, leaning toward the higher end if your gut is trained for it, plus sodium that climbs with the heat (often the high end of 300 to 700 mg per liter of fluid). The aid stations are well stocked with real food, including potatoes, chips, and later soup and quesadillas, but the gaps between them can be long, so carry enough fluid and calories to bridge them. It is a cupless race, so bring your own soft flask or cup. 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 Folsom Lake Ultra Trail 110K?

The overall limit is 20 hours 15 minutes from the 5:00 AM start, with intermittent cutoffs at aid stations along the way, so you cannot bank all your buffer for the end. Those intermediate cutoffs are how the race keeps the day on schedule, and they are enforced. Because the course direction flips clockwise versus counterclockwise each year, the order and timing of those cutoffs change, so pull the current year’s cutoff sheet and build your plan backward from it. Confirm every number in the official race-day details before you start.

What is the terrain and weather like at FLUT?

The loop is about 82 percent trail and 18 percent road, a mix of single-track and fire road that fully encircles Folsom Lake, with the direction (clockwise or counterclockwise) alternating year to year. Expect rolling, mostly runnable terrain, some rocky and technical patches, plenty of exposed shoreline and oak-grassland, and a handful of road and bridge connectors. Mid-September in the Sierra foothills tends to be hot and dry, often well into the 80s or 90s in the afternoon, with strong sun and little shade in the open sections. Managing the heat through the middle of the day is a real part of finishing this one.

Is the Folsom Lake Ultra Trail 110K a good first 100K?

It is one of the friendlier ways to step up to 100K, but do not mistake friendly for easy. The runnable terrain and the generous 20:15 cutoff give a prepared runner real room, and the loop around the lake with 12 aid stations (9 of them crew-accessible) makes it easy to support. What it asks for is long-run endurance, a fueling and hydration plan you have rehearsed in the heat, and a willingness to keep moving when it gets hot and, for many, dark. Train the distance and the heat, sort out a light or headlamp plan for the back half, and most committed runners can get the wooden buckle.

This guide is independent and for planning only. The course details, date, direction, cutoffs, and aid stations come from public sources and can change year to year, including the clockwise versus counterclockwise direction, 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.