Afternoon storm risk is the line that matters. Everything else is comfort. In summer, plan to be off the ridge before the build-up starts, not as it starts. Forecast for the summit point, adjusted for its elevation · data from Open-Meteo.
Colorado 13er · Northwest Face from Rustler Gulch
Overview
Cassi Peak is a rocky 13er at the head of Rustler Gulch, between Precarious Peak and Golden Tops. From the upper gulch you climb into the boulder basin below Precarious Peak's south cliffs, then grind up rubble on the west side to the north ridge just below the summit.
It is Class 2+ and all loose rubble and boulders; there is no easy line. Early in summer, snowfields make the going easier. It is often climbed with Precarious Peak, Golden Tops, or both.
The round trip is about 8.8 miles with about 3,550 feet of gain. Mileage and gain are our estimates. Many people backpack a short way up Rustler Gulch and camp, then climb several of its six 13ers over a few days.
Plan of the day
Start by
From a Rustler Gulch camp, by 6:30 a.m.
Turnaround
Be in the basin below Precarious Peak by 10 a.m.
Crux
Endless loose rubble and boulders.
Route-finding
Moderate. Head into the basin below Precarious Peak's south cliffs, then aim for Cassi's north ridge about 200 feet below the summit.
From Gunnison, take Highway 135 north to Crested Butte. Stay on the main road through town and continue north on County Road 317 to Mt. Crested Butte. Past the condos the pavement ends; measure from there.
At about 3.4 miles you pass Gothic, a research town with a small visitor center. Parking is limited to marked spots along this busy road. Gothic Campground (6 sites) is at about 5.3 miles. From June 15 to August 15, you may only camp in designated sites anywhere in this part of the East River valley.
At about 6.2 miles, FR 317.2B turns off for Rustler Gulch. Regular cars park here, and you wade the East River. Beaver dams have made the old vehicle ford a deep pool (as of 2025), so only a high-clearance 4WD should try it, ideally with a winch. Past the ford the road climbs steeply 0.7 mile to a gate with room for two or three cars.
Trail in the treesScramblingOff-trail, no set pathTalus and screeRidgeExposed to lightning
The line is elevation, the band underneath is the ground, and the numbered dots match the steps below. Mileage and elevations are approximate.
1
Rustler Gulch turnoff 9,716' · 0 mi
Wade the East River and walk up the road.
Watch for: Can be deep in early summer.
2
Gate 10,050' · 0.9 mi
Past the gate, follow the old road north through a meadow, then a muddy, horse-churned stretch of forest.
3
Creek crossing 10,300' · 1.6 mi
Flower meadows lead to a creek crossing. You may need to take off your boots, or follow a side path right along the creek to a spot with small logs.
4
Upper Rustler Gulch 10,700' · 2.2 mi
The trail heads north, then turns east into the upper gulch through huge wildflower meadows.
5
Campsite 10,865' · 2.5 mi
Where the trail has clearly turned east and the creek tumbles over rock ledges below, cross the creek and climb east through fallen timber. Near the east edge of the trees is a small campsite for two tents, the only good spot here that doesn't flatten flowers.
Watch for: Take care not to trample the meadows.
6
Leave the trail 11,400' · 3.2 mi
Follow the trail into the upper gulch and leave it near treeline.
7
Basin below Precarious 12,350' · 3.9 mi
Climb into the bouldery basin below the cliffs on Precarious Peak's south side.
8
Rubble slope 12,800' · 4.2 mi
Head south and up the west side of Cassi, past snowfields if there are any, on loose rubble and boulders.
Watch for: Tiring and unstable.
9
Summit 13,242' · 4.4 mi
Reach the north ridge about 200 feet below the top and follow it to the summit.
Getting down
Return the same way, or go down to the Cassi-Golden Tops saddle: follow the southwest ridge until forced off, then descend a short, very steep and loose gully and a broader, easier one on the west side to just below the saddle.
If things go wrong
The basin below Precarious leads back to the trail.
3D flyover
No 3D flyover for this peak
Above the Rustler Gulch trail the route is trailless. A flyover only works when there is a set trail to trace. Without one, the line would be a guess, and a guess could send you the wrong way on the mountain. Use the step-by-step route with a good map and GPS track instead.
See the trail on video
No video yet
We haven’t found a good video of this route that matches the way we describe it. The route strip, junctions and 3D flyover show the way in the meantime.
This describes the route on a dry summer day. Most 13ers see few people, so there may be no one along behind you. Check recent conditions the week you go, carry a map, tell someone your plan, and turn around when the day tells you to.