Summit Line

⏵ Course guide · Oregon ultra

McDonald Forest 50K Course Guide

The McDonald Forest 50K, the Mac to people around Corvallis, is one of Oregon’s oldest and most loved trail ultras, run on soft forest singletrack and logging roads through OSU’s McDonald Forest. It is not one monster climb. It is a steady stack of hills over named peaks like McCulloch, plus a stretch of twisty hobbit trails, and a damp, cool spring feel. I will walk you through the course first, then give you a pacing and fueling plan that fits all that up and down. There are free calculators along the way to dial in your own numbers.

⏵ At a glance

McDonald Forest 50K quick facts

Date
Saturday, May 2, 2026 (30th running)
Location
Peavy Arboretum, OSU’s McDonald Forest, Corvallis, OR
Distances
50K (about 31.6 mi)
Elevation gain
Roughly 6,400 to 7,800 ft depending on the year’s route
Start
8:00 AM, with a 7:00 AM early start option
Time limit
Generous (early starters sign up for a 7.5 hr finish); confirm the current cutoff
Aid stations
4 well-stocked aid stations along the loop
Qualifier
No Western States, UTMB, or Hardrock qualifier status listed

These facts come from the official race site and UltraSignup. The exact route, vert, and time limit shift a little year to year, so check the current race-day details before you commit. Race logistics change.

The course: where the Mac is won and lost

The 50K is a big forest loop out of Peavy Arboretum, roughly 31.6 miles with somewhere around 6,400 to 7,800 feet of climbing. Figure about 22.7 miles of soft singletrack and 8.9 miles of logging road. The gain is spread across a string of named high points rather than one giant ascent, which changes how you pace it.

The climbs: a stack of hills, not one wall

The whole day is a series of climbs and drops over named bumps: Peavy Peak around 1,280 feet, Vineyard Mountain around 1,453, Dimple Hill around 1,478, and the high point, McCulloch Peak, at about 2,178. None of them is a savage wall on its own. The catch is that they add up, so the race is won by keeping your effort even across all of it instead of attacking any single hill. Hike the steep pitches, run the gentle grades, and you arrive at the back half with legs still under you.

Some of this happens on wide logging road, which is honestly a gift. The roads give you sections where you can settle into a rhythm and eat and drink without watching your feet. Use them. Bank easy, relaxed miles on the road climbs and save your focus for the singletrack.

The hobbit trails: the fun, twisty heart of the course

The signature stretch is the run through Starker Forest’s hobbit trails, the section a lot of people call the Maze. It is narrow, twisting, and a little technical, the kind of trail that is not the fastest running but is the most fun part of the whole day. Quick feet and a little patience go a long way here. Do not try to force a road pace through it. Flow with the turns and enjoy it, because this is the part of the Mac people come back for.

After the high country and the Maze, the course works back toward Peavy, and the finish drops you down a soft, pine-needle-cushioned trail. It is a sweet way to come home if you paced the day right.

Mud, footing, and the cool spring weather

This is western Oregon in early May, so plan for soft, damp trail and the odd boggy or muddy patch, especially in a wet spring. The footing is mostly forgiving compared with a rocky desert or alpine course, but a slick root or a muddy corner will still catch you if you stop paying attention. Shoes with real grip earn their keep.

Weather usually means cool and overcast, sometimes low cloud or light drizzle up on the higher peaks even when the start is dry. It rarely gets hot, so the real game is staying warm and keeping your feet moving rather than fighting heat. Dress for cool and damp, and be ready to shed a layer once the day warms up.

Pacing strategy for a rolling, climb-heavy 50K

With the vert spread across a lot of climbs and descents, the Mac is about managing effort over rolling terrain, not chasing a flat pace chart. Run the hills by feel, hike the steep stuff early, and let the road sections give your legs a break.

Pace the hills by grade, not by the watch

Your flat-ground pace is meaningless on this much rolling climb. What matters is grade-adjusted effort, so hold an output you can sustain up the grade and hike the steep pitches without feeling like you are losing the race. The classic mistake on a course like this is running the first few climbs too hard because they feel short and easy, then fading on the back-half hills. Use a grade-adjusted pace to turn your real fitness into honest climbing and descending targets, and you will save plenty for the second half.

Build a vert-aware finish prediction

Do not guess your Mac finish off a road 50K time. Six-thousand-plus feet of climbing, the twisty hobbit-trail miles, and a few muddy stretches all add real time. A vert-aware finish prediction that accounts for this course’s climbing gives you a realistic window, and it lets you decide whether the 7:00 AM early start makes sense for you so you are never racing the clock.

⏵ Free tools to pace this course

Fueling strategy for a cool, 5 to 7 hour day

Most runners are out on the Mac for somewhere around 5 to 7 hours across four aid stations. The cool weather actually helps your gut, so the bigger risk is under-fueling because you do not feel thirsty, not heat shutting your stomach down.

Carbs: steady and trained

For a 5 to 7 hour effort, aim for around 60 to 90 grams of carbohydrate per hour, and only push the higher end if your gut is trained for it. On a cool day it is easy to forget to eat, so set a schedule and stick to it rather than waiting until you feel low. Practice your exact race-day carb rate on long rolling runs so 70 or 80 grams an hour feels routine, not like an experiment you are running for the first time on race morning.

Fluid and sodium: do not coast just because it is cool

Cool, damp weather makes it easy to drink too little, but you are still climbing for hours and sweating more than you think under your layers, so keep sipping on a schedule. Moderate sodium, often in the 300 to 600 milligrams per liter range, covers most runners on a cool day, with more if you are a heavy or salty sweater. The aid stations are well stocked and there are four of them, but still carry enough between them to fuel the climbs. Weigh yourself before and after a long run to find your real sweat rate and 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 a cool-day effort 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 Mac Forest course profile, and your projected splits. Summit Line reads your real training, builds a plan for all the rolling climbs, and rehearses your fueling so race day is something you execute, not guess at.

Start free →Explore the demo

McDonald Forest 50K FAQ

How hard is the McDonald Forest 50K?

The Mac is a real mountain 50K, not a flat road race, but it is friendlier than a high-altitude alpine ultra. You are covering about 31.6 miles with somewhere around 6,400 to 7,800 feet of climbing (the exact number shifts with each year’s route) on a mix of soft singletrack and logging roads in OSU’s McDonald Forest near Corvallis. The climbing comes in a handful of named bumps rather than one giant ascent, topping out on McCulloch Peak at about 2,178 feet, so it rewards steady climbing and honest pacing more than raw speed. The time limit is generous and the vibe is grassroots, which makes it a great hard-but-doable goal race.

How much climbing is in the McDonald Forest 50K?

Plan on roughly 6,400 to 7,800 feet of total elevation gain across the 50K, depending on which trails the route uses that year. It is not one long climb. Instead you stack a series of climbs over named high points like Peavy Peak (about 1,280 ft), Vineyard Mountain (about 1,453 ft), Dimple Hill (about 1,478 ft), and the high point, McCulloch Peak, at about 2,178 ft. Because the gain is spread out, the trick is keeping your effort even over a lot of up and down rather than emptying the tank on any single hill.

What are the time limit and early start for the McDonald Forest 50K?

The standard start is 8:00 AM and there is a 7:00 AM early start option for runners who want extra time on course. UltraSignup lists the early start for people expecting roughly a 7.5-hour finish, so the field is built around a generous, mid-pack-friendly day rather than a brutal cutoff. The race has a reputation for being relaxed about enforcing cutoffs, but that can change, so confirm the current time limit and any aid-station cutoffs in the race-day details before you toe the line.

What is the terrain like at the McDonald Forest 50K?

It is classic western Oregon forest running: soft, lovingly maintained singletrack through Douglas fir, mixed with stretches of wide logging road. A rough breakdown is about 22.7 miles of trail and 8.9 miles of road. The standout is the section on Starker Forest’s hobbit trails, sometimes called the Maze, which is narrow, twisting, and a little technical but a blast to run. Footing is generally good, though spring rain can leave boggy, muddy patches, so expect a few slick or soft spots.

What is the weather usually like for the McDonald Forest 50K?

Early May in the Willamette Valley and Coast Range foothills is cool and often damp. Mornings start chilly and overcast, and you can hit low cloud or light drizzle up on the higher peaks even when it is dry down at the start. It rarely gets hot, so the bigger concerns are wet feet, muddy trail, and staying warm if a cold rain sets in rather than fighting heat. Dress for cool and damp and be ready to peel layers as the day warms.

Is the McDonald Forest 50K a good first 50K?

Yes, it is one of the better Oregon ultras to pick for a first 50K. The footing is mostly forgiving, the climbing is spread into manageable chunks rather than one savage wall, the weather is usually cool, and the generous time limit and friendly grassroots atmosphere take a lot of pressure off. You still have to train for the vert and the duration, so put in long runs on rolling trail and practice your fueling, but if you respect the climbing the Mac is a very achievable and rewarding first 50K.

This guide is independent and for planning only. The course details, date, time limit, 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.