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Rio Del Lago 100 Mile Endurance Run Course Guide

Rio Del Lago is a fast 100 miler in the Sierra foothills, running from Folsom Lake out toward Auburn and back on the famous Western States Trail. Runnable singletrack and bike path, real climbing that stacks up late, a cold November night, and the historic No Hands Bridge. I will walk you through the course, then give you pacing and fueling strategy built for exactly those conditions, plus free tools to dial in your own numbers.

⏵ Quick facts

The Rio Del Lago 100 at a glance

Date
Sat, November 7, 2026 (100 Mile + 50K)
Location
Folsom Lake State Rec Area, Granite Bay / Auburn, CA
Start / Finish
Beal's Point, about 40 minutes east of Sacramento
Start time
5:00 AM (100 mile)
Distances
100 Mile and 50K
Elevation gain
About 13,874 ft of climb, with the same in descent
Terrain
Singletrack, fire road, bike path, oak woodland and river canyon
Time limit
Sub-30 hours for the official buckle
Qualifier
2026 edition is a 2027 Western States 100 qualifier

Note: the 100 mile and 50K both run on Saturday, November 7, 2026, out of Beal's Point at Folsom Lake. Specific per-aid cutoffs and the exact aid-station count can change year to year, so always confirm the date, route, aid-station chart, and cutoffs on the official Rio Del Lago site before you plan your race.

The course

The Rio Del Lago 100 starts at Beal's Point on Folsom Lake and runs from Folsom out toward Auburn and back, stringing together paved bike path along the American River Parkway, rolling singletrack through oak woodland, and stretches of the storied Western States Trail in the Auburn State Recreation Area. It is a low course and a largely runnable one, about 13,874 feet of total climbing and the same in descent. No real altitude, but plenty of vert packed into rolling climbs and canyon drops.

A fast, deceptive opening

You start in the dark at 5:00 AM and roll early through runnable terrain, bike path and lake-loop singletrack along the American River Parkway, with Folsom Lake sitting out there as the backdrop. This is the trap of Rio Del Lago. The front of the course is so smooth and fast that it is easy to bank time you cannot actually afford. The people who run the opening miles hard, treating a runnable 100 like a 50K, are usually the ones coming apart in the Auburn canyons late at night.

So the smart move is to run the early bike-path and rolling sections relaxed and well within yourself, and treat them as easy aerobic miles instead of free speed. The climbing and the cold night are both still out there waiting, and your legs will want every match you save back here.

Into the canyons: Cardiac Hill and Last Gasp

As the course works toward Auburn it leaves the easy path behind and climbs into the American River canyons on the Western States Trail. Named efforts like Cardiac Hill and the Last Gasp climb up to the Auburn Dam Overlook are where the rolling vert gets serious, and the descents off the overlook drop you down toward the historic No Hands Bridge over the river.

These canyon sections are the heart of the course and the part runners remember. Power-hike the steep pitches with purpose, run the grades you can run, and respect the descents, because the out-and-back shape means you cover this kind of ground more than once. Know where the long carries between aid fall and fuel up all the way before them. And do not let the runnable reputation talk you out of eating on the climbs.

The night and the back half

Rio Del Lago is a November race with a long cutoff window, so most of the field runs deep into a cold, dark night with not much daylight. The back half retraces the kind of ground you covered going out, but now it is on tired legs, in the cold, and often alone or with a pacer. This is where the race is won or lost. The runners who stayed disciplined and well-fueled early still have working quads and a clear head, and the ones who pushed that fast opening are grinding.

Plan your layers, your lighting, and your late-race fueling for cold, not heat. Keep eating through the low hours when your appetite quits on you, keep moving with margin against the intermediate cutoffs, and let the simple runnable nature of the closing miles work for you instead of against you.

Aid stations and cutoffs

The course is backed by a series of well-stocked aid stations with water, electrolyte fluids, food, and medical aid, and drop bags are allowed at the major checkpoints. Just know that some stretches, like the run past No Hands Bridge, have long carries with no aid in between, so fill up and fuel before you leave. The big time goal is a sub-30-hour finish for the official buckle, off the 5:00 AM Saturday start.

The intermediate aid stations carry their own cutoffs. Check the official Rio Del Lago aid-station and pace chart for the current edition and build your pacing plan backward from those times with a buffer, because the climbing in the canyons and the long cold night can quietly eat a cushion you thought you banked early.

Pacing strategy for the Rio Del Lago 100

A runnable, climb-stacked, low-altitude 100 miler pays you back for holding back on the fast early miles and staying disciplined in the canyons. Pace this course by effort and by grade, not by how fast the opening bike path makes you feel.

Bank patience, not pace, on the fast opening

The most common Rio Del Lago mistake by far is running the runnable front half too fast. Hold the early bike-path and rolling singletrack at a genuinely easy effort, slower than it feels like you need to, and you will have the legs to actually run the back half while most of the field is down to a shuffle. The clock you want to beat is at mile 80, not mile 20.

Use our free grade-adjusted pace calculator to turn your flat fitness into honest effort targets for both the easy early miles and the steeper canyon climbs, so you can tell whether you are pacing something you can hold or quietly spending matches you will want back late.

Protect your quads for the canyon descents

With about 13,874 feet of descent matching the climb, and an out-and-back shape that doubles the rolling terrain, the downhills are the part that really gets you. Run the descents controlled and light instead of letting gravity hammer your legs, especially the drops off the Auburn Dam Overlook toward No Hands Bridge. The runners who finish strong are the ones who still have working quads when the back half asks them to keep moving. The climbs are not what get you, the descents are.

To set a finish goal that actually accounts for the 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 number that the Auburn canyons will quietly tear up.

Plan for the cold night, not for altitude

Rio Del Lago never reaches real altitude, so you do not have to pace around thin air the way you would in an alpine 100. The thing to plan around is the long November night: short daylight, dropping temperatures, and a lot of hours in the dark. When the cold sets in your pace can hold, if you stayed disciplined early and kept eating. But it falls apart fast if you get to nightfall already depleted.

And if you want to see how your fitness from a recent race lines up with a 100 mile effort like this, our race equivalent calculator helps you reality-check your goal before you commit to a finish time.

Fueling strategy for the Rio Del Lago 100

An all-day-and-night effort in cool November weather makes steady fueling and smart hydration matter just as much as fitness. The mild temperatures cut your fluid needs, but they also tempt you to under-fuel on the long runnable stretches, so plan it out on purpose.

Carbs: steady and high, on a trained gut

For an effort this long, aim for about 60 to 90 grams of carbohydrate per hour, leaning to the high end once your gut is trained to take 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 training runs so 80 to 90 g/h feels normal by race day, not like something you are trying for the first time.

The runnable feel of Rio Del Lago is a fueling trap. When the miles feel easy it is tempting to coast and forget to eat, and then the canyons and the cold night show up and you are already in a hole. Set a timer, keep the calories coming through every section, and treat fueling as a job you do not get to skip, even when the trail feels gentle.

Sodium and fluid: tuned for cool weather

In November your sweat losses are usually lower than a summer race, so you can run a sodium concentration around 400 to 700 mg per liter of fluid and match your fluid volume to the cool air instead of over-drinking. Watch the long carries with no aid, like the stretch past No Hands Bridge, and carry enough to cover them. Cramping, a sloshy stomach, and that wrung-out late-race feeling are usually 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 conditions you expect, and it gives you a carb, sodium, fluid, and caffeine number per hour built for the Rio Del Lago duration and the cool-weather profile. Then go test it in training.

⏵ Free calculators for this race

Run your Rio Del Lago numbers with our free, no-signup tools, then let Summit Line tie them all back to your real fitness and this exact course.

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⏵ Train for the Rio Del Lago 100

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Rio Del Lago 100 FAQ

How hard is the Rio Del Lago 100 Mile Endurance Run?

Rio Del Lago is one of the more runnable 100 milers in California, and that is exactly what makes it sneaky. The official 100 mile course has about 13,874 feet of climbing and the same in descent, which is a lot less than a high alpine race, and the Sierra-foothills profile sits low the whole way so you never hit real altitude. But that runnable feel pulls people into going out too fast on the early bike paths and rolling singletrack, and then the climbing piles up late as you push toward Auburn and back. The November date keeps the heat down, but you pay for it with a long cold night and short daylight. With a sub-30-hour buckle to chase and the famous Western States Trail underfoot, finishing this one means something, and it is a recognized Western States qualifier.

How much climbing is in the Rio Del Lago 100?

The official race site lists about +13,874 feet of gain and the same in descent across the 100 mile course, and plenty of runners say their watch records more. There is no one big mountain here. The vert comes from a long string of rolling climbs and canyon drops along the American River and the Western States Trail, with named efforts like Cardiac Hill and the Last Gasp climb up to the Auburn Dam Overlook. And because the course runs out from Folsom toward Auburn and back, you climb and descend the same kind of ground twice, so honestly the descending beats up your quads just as much as the climbing taxes your legs.

How should I fuel for the Rio Del Lago 100?

Fuel it like what it is, a long, mostly runnable effort that goes all day and all night in cool weather. Most runners aim for 60 to 90 grams of carbohydrate per hour, leaning to the high end once the gut is trained for it, with a sodium concentration around 400 to 700 mg per liter of fluid. November in the Sierra foothills is usually mild instead of brutally hot, so you need less fluid than a summer race. But do not let the cool air trick you into under-drinking or under-fueling on the long runnable stretches, because those are the parts where you are actually working. Practice your hourly carb number on long training runs first. Our free ultra fueling calculator takes your weight, goal time, and the conditions you expect and turns them into a carb, sodium, and fluid plan per hour.

What are the Rio Del Lago 100 cutoffs?

The big one is a sub-30-hour finish for the official belt buckle, off a 5:00 AM Saturday start. There are intermediate cutoffs at the aid stations along the way, and the official Rio Del Lago aid-station and pace chart for the current edition spells out each one. Because the course is so runnable up front, the thing that gets you is not the early cutoffs, it is burning your legs before the climbing and the night even start. Build your pacing plan backward from the published cutoffs and give yourself a comfortable buffer. And confirm the exact times on the official race site, since they can change year to year.

Is the Rio Del Lago 100 at altitude, and is it hot?

No to both, mostly. Rio Del Lago runs through the Sierra foothills and along the American River, a low course that never climbs into real altitude, so thin air is not a factor the way it is in an alpine 100. Heat is usually modest too, because the race is in early November when Northern California has cooled off. The catch is the night. A 30 hour window in November means a long, cold, dark stretch with not much daylight, so plan your layers, your lighting, and your late-race fueling for cold, not for heat.

Does the Rio Del Lago 100 count as a Western States qualifier?

Yes. The 2026 Rio Del Lago 100 is listed as a qualifier for the 2027 Western States 100, and the course shares real ground with Western States, including the Western States Trail and the historic No Hands Bridge. Finish inside the cutoff and you put a qualifier on your record for the next year. That, plus running the same trails the Western States legends do, is a big part of why this race is so popular.

This guide is for planning and training purposes and reflects publicly available information about the Rio Del Lago 100 Mile Endurance Run. Race details, including the date, course, aid stations, and cutoffs, can change year to year. Always confirm the current specifics on the official Rio Del Lago race website before you train or travel.