O'Leary Mountain

United States Oregon O'Leary Mountain

O'Leary Mountain Bike Climb - PJAMM Cycling

32.2

PDI

6.8 mi

DISTANCE

3,704 ft

GAINED

ELEVATION GAINED

10.4 %

AVG. GRADE

AVG. GRADIENT

FULL CLIMB STATS

Page Contributor(s): Don Baty, Corvallis, OR

INTRO

O'Leary Mountain is a 6.8-mile gravel climb in Oregon's Willamette National Forest, gaining 3,704 feet at a 10.4% average grade on Forest Road 1900-411 above Cougar Reservoir in Lane County. It's currently ranked the 29th-hardest climb in our worldwide database - one of the steeper, more remote forest roads we've climbed. The road begins at the base of Cougar Dam, a 519-foot Army Corps of Engineers rockfill dam completed in 1963, and works up the South Fork McKenzie River drainage through dense old-growth forest. The opening miles are deceptively mellow, but with a little over three miles to go the grade pitches up hard - we found sustained pitches from 10% to 23% on our own ride, with loose gravel that makes traction genuinely difficult. Arrive with a low gear or expect to walk. Near the top, FR-411 narrows to something closer to overgrown double-track than road - the forest is visibly reclaiming it - though it stays rideable on a gravel bike all the way to the O'Leary/Castle Rock Trailhead, which also serves the O'Leary Trail Complex, a 22-mile singletrack loop with an IMBA 'Epic Ride' designation. This climb follows the gravel road rather than that trail - the remote payoff without technical singletrack riding.

PLAN YOUR ROUTE

We've partnered with Sherpa-Map.com to bring you the best route planning tool. With a PRO Membership you can use this climb as a reference when creating your route.

O'Leary Mountain's overall average of 10.4% hides a lopsided profile. The first stretch out of the Cougar Dam area is comparatively gentle, winding through forest along the reservoir with gradients mostly in the single digits. Real climbing starts a little over three miles in, when the road turns up sharply - our own ride recorded pitches ranging from 10% up to 23% through this section, which is also where the gravel gets loosest and hardest to hold traction on. The final push to the summit near the O'Leary/Castle Rock Trailhead stays steep and rough. Use the Profile Tool above for the full mile-by-mile gradient breakdown, and expect the back half of this climb to feel considerably harder than the overall average suggests.

Roadway: Forest Road 1900-411 is unpaved for its entire length - packed dirt and gravel through the lower, gentler miles, turning looser and rougher as the grade steepens over the final three miles. In the last half-mile before the O'Leary/Castle Rock Trailhead, the road narrows to something closer to overgrown double-track than a maintained forest road, though it remains rideable on a gravel bike. Traffic: Very light. This is a remote Forest Service road deep in Willamette National Forest, well off Highway 126, so vehicle traffic is minimal - you're more likely to cross paths with a mountain biker headed for the O'Leary Trail Complex trailhead than a car. Parking: Park near the base of the climb by Cougar Dam and the Cougar Powerhouse and Fish Facility, where several pullouts along the South Fork McKenzie River serve as informal parking areas.

Bring a gravel or adventure bike set up with a genuinely low climbing gear - the final three miles pitch up to 23% on loose gravel, and there's no shame in walking a section if traction goes. There's no water or services anywhere on the climb itself, so carry everything you'll need. The closest provisions are back on Highway 126: a gas station and Blue Sky Market in Rainbow, or the McKenzie General Store and Obsidian Grill in McKenzie Bridge, both a short drive from the Forest Road 19 turnoff at Blue River.

Before heading out on any cycling adventure check out our Things to Bring on a Cycling Trip and use our interactive check list to ensure you don't forget anything.

Reach the start from Blue River, Oregon: take Forest Road 19 (Aufderheide Drive) south off Highway 126, continue onto Forest Road 410 to the base of Cougar Reservoir, then east onto Forest Road 1900-411. Plan for late spring through fall - Forest Service roads at this elevation aren't maintained for snow or ice, and the route holds snow into early summer some years. The surrounding Cougar Recreation Area currently prohibits dispersed camping outside designated campgrounds (in effect through February 2027), so plan on a formal campground or lodging in Blue River or McKenzie Bridge. Terwilliger (Cougar) Hot Springs is a worthwhile stop nearby, and it's always worth checking Willamette National Forest's current alerts for fire restrictions or road closures before you go, especially late in the season.