Course Recon
· May 31, 2026 ·
Arnold, California
An ancient lava cap, three Sierra drainages, one cathedral forest.
Run the Rim 50K.
A point-to-point through the Stanislaus National Forest — from the Lone Madrone trailhead at Fullen Road to the shores of White Pines Lake.
31.17
Miles
5,929
Ft Climb
4,528
High Point
2,591
Low Point
9:00
Time Limit
08:00
Gun Time
01
Elevation · ft
Source: Trailforks GPX 65521
Runnable
Steady
Conserve
Push
Hike
Note on data: Course geometry is the official Trailforks route (2,584 trackpoints). Elevation profile is anchored to documented landmark elevations and shaped to actual route geography pending official elevation data from the RD.
02
38.18°N · 120.41°W → 38.27°N · 120.34°W
31.17 mi · POINT-TO-POINT
Stanislaus N.F.
"
Not every trail race takes you across an ancient lava cap. Welcome to the Arnold Rim.
03
0
Mile
Start — Fullen Rd, Post 100
Lone Madrone Trailhead, Avery, CA. Shuttle from White Pines departs 7:30 AM sharp.
3,289
ft
ft
Shuttle Only
6.6
Mile
Avery Sheep Ranch Rd
The only vehicle crew access on course. Hits early — runners arrive 90 min to 2 hrs in. After this, no vehicle access for 24+ miles.
~3,700
ft
ft
Crew Vehicle
Drop Bag
~22
Mile
Lava Cap Rim — High Point
The course's highest aid. Mt. Diablo views west, Sierra crest east. Fuel up before the long Rim singletrack.
~4,500
ft
ft
Foot Access
31.17
Mile
Finish — White Pines Lake Park
Jump in the lake. Pizza Factory post-race opens 11 AM. Hard cutoff 5:00 PM.
3,877
ft
ft
Finish
Mid-course aid stations between miles 13–18 are confirmed by the RD with exact placement TBD — expect 1–2 stations through the rolling middle and approaching the lava cap climb.
04
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Segment 1
0—2.5
The Plunge
Runnable
A fast descent off Fullen Road into the canyon — your fastest mile of the day is mile one. This is a trap. Control your effort, protect your quads, and don't let the downhill pull you into a pace you'll pay for at mile 20. The course low point sits at the bottom. Run it at a comfortable float. It should feel embarrassingly easy.
Segment 2
2.5—6.6
Climb to Avery
Hike
Steady climb out of the canyon up to the Avery Sheep Ranch Rd aid station. Power hike with purpose. Eat now — you'll want calories absorbed before you arrive. This is your only vehicle crew access of the day, and it comes early. Treat it like a real pit stop, not a quick pass-through.
Segment 3
6.6—12
The Rolling Middle
Steady
The most runnable section of the course. Rolling singletrack through the canopy, several drainage crossings. Settle into a sustainable rhythm — this is where you bank time without burning matches. Don't push it. Bank effort for the long climb that's coming.
Segment 4
12—14.5
The Drainage Drop
Conserve
Major descent. Light feet, short stride, save the quads. You'll regret eccentric-loading these miles when you hit the long climb that follows. Treat it as active recovery — eat, hydrate, mentally reset for the hardest part of the day.
Segment 5
14.5—22
The Long Climb to the Rim
Hike
The race-defining climb. ~7.5 miles of net climbing to the lava cap ridgeline at ~4,500 ft — the highest point on course. Power hike it. Don't try to run-hike — just hike with poles if you have them and keep moving. The payoff is massive: Mt. Diablo to the west, the Sierra crest to the east. Take five seconds to look. Then keep moving. Eat constantly through this section. This is where the race gets won or lost.
Segment 6
22—28
The Rim Reward
Steady
You're past the hardest terrain. Cathedral forest of Ponderosa Pine, Sugar Pine, and Incense Cedar — growing since before California was a state. Rolling singletrack along the Rim. Stay steady. Don't let the perceived ease lull you into skipping nutrition — fueling now is what makes the final descent runnable.
Segment 7
28—31.17
Descent to White Pines
Push
The final 3 miles drop down toward White Pines Lake. Open up the stride, trust the legs, and earn the lake. Every finisher gets to jump in. The Pizza Factory opens at 11 AM. Hard cutoff is 5:00 PM. Leave it all here.
The Ten-Word Race Plan
Easy down. Hike up. Eat always. Push the finish.
05
Manageable altitude
Max elevation is 4,528 ft. You won't be fighting thin air — making this a legitimate introduction to mountain ultras, or a solid early-season altitude primer.
The profile trends up
The early descent is a trap. The course climbs more than it drops on net — finish is 588 ft higher than the start. Don't blow your quads in the first 4 miles.
Late May in the Sierras
Expect morning temps in the 40s–50s at Fullen Rd, warming into the 60s–70s on the exposed lava cap ridgeline. Sunscreen and a layer for the start.
Crew the early aid
Avery Sheep Ranch Rd at mile 6.6 is your only vehicle crew. Stock the drop bag for the long haul — 24+ miles after with no vehicle access.
Lake finish
Every finisher ends at White Pines Lake. The water is for swimming, not just looking at. Pack a towel in your finish-line bag.
For ARTA
Proceeds support the Arnold Rim Trail Association — the all-volunteer non-profit maintaining 31+ miles of trail through Stanislaus N.F.