Sourdough Trail

Roosevelt National Forest, Colorado

Elevation Gain4,713ft
Trailhead Elevation8,550ft
Elevation Min/Max8550/10298ft
Elevation Start/End8550/8550ft

Sourdough Trail

Sourdough Trail is a hiking and biking trail in Boulder County, Colorado. It is within Roosevelt National Forest. It is 12.6 miles long and begins at 8,550 feet altitude. Traveling the entire trail is 25.2 miles with a total elevation gain of 4,713 feet. The Sourdough Trailhead Parking is near the trailhead. The Columbia Mine (elevation 9,488 feet) quarry and Brainard Lake Area Winter Trailhead and another parking can be seen along the trail. There are also a warming hut and restrooms along the trail. This trail connects with the following: Little Raven Trail, South St. Vrain, Usfs Trail 909, Wapiti Trail, Buchannan Pass Trail, Waldrop Trail, Usfs Trail 814.1 and Cutoff Trail.

Sourdough Trail Professional Reviews and Guides

"A traditional out-and-back route on a mountain trail, up and down through subalpine forest. This ride serves as a good introduction to the high-altitude trail network in the vicinity of Brainard Lake. “Only 11.4 miles,” you say. “That’s an after-dinner jaunt.”

Well, this ride is a bit longer than the number that appears on your odometer when it’s all done. The stretch of the Sourdough Trail between Rainbow Lakes Road (CR 116) and Brainard Lake Road never gets ridiculously technical or steep, like some other rides on the Front Range, but it’s consistently rocky. A bumpy yet non-technical ride."

"The Sourdough Trail skirts the fringes of the beautiful Indian Peaks Wilderness Area. The drive alone from Boulder to the trailhead is reason enough to head for this trail. While traveling along the Boulder Canyon, multisport adventurers can stop to enjoy great climbing and hiking opportunities before continuing on Colorado’s famed Peak-to-Peak Highway. Once on the trail, however, the fun really starts.

The Sourdough Trail is almost entirely covered by a thick forest canopy, providing cool, shaded relief the whole ride through. Although the climb to Brainard Lake is challenging (but enjoyable), the descent is why you ride it. A fast and smooth descent through a thick emerald forest will have you screaming, “There’s no place like here and now.” Terrain: Singletrack, plus some paved and dirt road if optional loop is taken."

"The best singletrack in Boulder County. A great summer ride through dense pine forest with occasional views of outstanding scenery to the east. Why overheat on the lower elevation trails when you can do the Sourdough? Tread: 12.2 miles of excellent singletrack."

"Did I mention rocks? This popular rocky trail jars you over most of the length of the ride. The rocks are generally not large, often loose and always seem to be under your knobbies. Try this trail if you are looking for practice over rocky surfaces. The climbing is not steep, but several of the climbs are extended. Terrain: Rocks, rocks, rocks; occasional hardpack and waterbars."

"This great trail is along the eastern flank of Niwot Mountain. Dense pine forests, wildflowers, easy access to connecting trails, and views are the main attractions of this hike. Trail conditions: This popular trail is smooth in some sections and extremely rocky in others."

"The Sourdough Trail, though popular, has much less traffic than trails in and around Brainard Lake. You won’t get quite the stunning views of the Indian Peaks, but you get beautiful views of the foothills, plains, and even snowcapped peaks in the distance.

As you can see from the altitude information (gained and lost) on the map, both trail segments roller-coaster, but the trail segment from Brainard to the south is more level overall, until you get near Rainbow Lakes, where the trail descends significantly."

"The North Sourdough follows natural contours as it twists through old-growth forests and across gurgling creeks, providing an alternative to the crowded trails in the Indian Peaks Wilderness and Rocky Mountain National Park.Many Front Range residents take this magnificent swath of national forest for granted and assume, incorrectly, that it is protected as part of the Indian Peaks Wilderness.

A few open spots expose the North Sourdough to wind. It has only a few glimpses of the high peaks so is best for folks who like just rambling through the woods. The descent from Brainard Road to Beaver Reservoir and Peaceful Valley is a moderate hike but a steep cross-country ski. Watch out for mountain bikes in summer."

"The Sourdough Trail has three sections as it runs north to south for over 15 miles along the eastern flank of the Indian Peaks. The trail provides a group of classic ski tours and good snowshoe routes with plenty of steep ups and downs. Snowmobiles are forbidden on the entire Sourdough Trail. There are occasional views of the adjacent mountains, but most of these trails pass through the forest, which limits the vistas. Many other trails connect with the Sourdough.

The area around Brainard Lake and the eastern slopes of the Indian Peaks is often windblown with irregular snow cover. The best times for this outing will be in the second half of the cross-country ski and snowshoe season, preferably after some recent snowfall. This northern segment is ideal for the snowshoer, but advanced skills are necessary for the nordic skier as the narrow trail has several steep and curving parts. Follow the blue diamond markers on the trees."

"The Sourdough Trail has northern, middle, and southern segments and runs north and south on the eastern side of the Brainard Lake area. This tour involves the southern part and a route from the upper to lower trailheads.

Using two vehicles is recommended. The Brainard Lake area is often very windy, and exposed areas may lack snow in the winter. Therefore, this trail is best in its upper tree-covered parts and after a good fresh snowfall."

"The Sourdough is for all levels of hikers and quiet winter recreation users. It’s a delightful excursion through dense spruce forests and provides welcome shelter from the fierce winds that often rake the Indian Peaks. It follows a natural bench, so it is a favorite with hikers, trail runners, crosscountry skiers—and with mountain bikes—so stay alert.

Done in short sections, the Sourdough can be a nice trek for families, while its total length can give speed hikers a workout. I almost didn’t include it in this book because I didn’t want more people on one of my favorite trails.However, the trail clearly illustrates that the Forest Service can use its authority to protect the peace and quiet of our national forests—qualities abundant on the Sourdough—even if a few human-made intrusions are present, such as the utility line near this trail’s southern end."

Sourdough Trail Reviews

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I've ridden this trail a few times. It has a good balance of climbing and descending. It's more of a rolling singletrack - more up than down on the way north, but it's not just climbing forever; there are a couple of short descents along the way to break up the monotony and pain. It seems to get rockier towards the end of the summer after more trail use. July had better singletrack conditions. The shade definitely makes for a nice cool riding day. There are a few technical sections to challenge you, and some tight switchbacks, but a lot of the trail is pretty tame. It's a great ride close to Boulder, and can link up with St. Vrain or Camp @$!*% - though those sections get a lot more technical.
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A nice steady climb and pretty views and some challenging rocky sections. A fun ride within 20 minutes or so of Boulder.
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Sourdough was more technical than the trail guides indicated. It was very rocky and requires good shocks. Lots of vertical at the trail head, but beautiful overall. This trail is not for the faint of breath at 10,000 feet and more.

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Trail Information

Roosevelt National Forest
Nearby City
Roosevelt National Forest
Moderate to Difficult
Skill Level
Additional Use
DeLorme: Colorado Atlas and Gazetteer, p. 29
Local Maps

Activity Feed

Oct 2018