Sourdough Trail

HARD 31 reviews
#44 of 111 trails in

Sourdough Trail is a 11.2 mile lightly trafficked out and back trail located near Boulder, Colorado that features a river and is rated as difficult. The trail offers a number of activity options and is best used from June until September. Dogs are also able to use this trail but must be kept on leash.

11.2 miles
1604 feet
Out & Back

dogs on leash



mountain biking

trail running



wild flowers


bridge out


29 days ago

Fun winter hike! There’s snowpack on the trail but not enough that we needed special equipment. Snow boots worked fine. We started at South Sourdough trailhead and hiked around 1.5 hours, then turned back. There were people doing off trail skiing and snowshoeing. The portion of the trail we did was fairly easy. Uphill but at a low grade.

2 months ago

Great walk and not too many people on the trail. Good dog walk too.

3 months ago

Started near Brainard Lake and went a few miles. Beautiful walk through the woods. I can see where this would be fun on a bike or snowshoeing. The trail is well marked.

5 months ago

moderate trail well marked. beautiful landscape and different terrain. well shaded and would recommend to anyone

5 months ago

Great Sun. Morning. Not sure why it's rated hard...very mellow but we only did 1/2 from Gateway parking lot (free right by Brainard Lake entrance). So we went about 5miles out and back. We needed a mellow walk and this was really nice and gentle. Full is all day so definitely picnic and stopping at Peace Memorial Bridge is a good location halfway to do that.

6 months ago

Solid, moderate trail to get to Brainard Lake without driving in via Roosevelt entrance. You can find the trailhead at the free parking lot to the right of the parks entrance. nice mellow hike through pines and aspens. beautiful creek.

trail running
7 months ago

a great trail for running. not many people. gentle ascent and wooded. a few creeks along the way for the pooches to get water.

9 months ago

There was a lot of snow.

Monday, February 06, 2017

This is a trail we always end up at for snowshoeing! It has a lot of snowpack and is dog friendly, an essential for a good trail. Not too many people this day, it was snowing a bit but the conditions were great otherwise. More of a trail, not too much to see through the trees and the trail is a bit hard to navigate the dog friendly parts, but good overall!

Friday, August 14, 2015

I hiked a bit on the segment by Beaver Reservoir this month. There's an extended foot bridge over Beaver creek which is marked "Closed". This seems to be due to some missing/rotted boards and missing hand rail over the deepest part of the creek. It is safer than trying to ford the creek but it's definitely "use at your own risk".

mountain biking
Sunday, September 07, 2014

As the description states, mainly used for trail running and mountain biking. This is a very strenuous trail that is not recommended for sight seeing or a nice leisurely family hike. This is a very difficult and extremely rocky trail.

Friday, July 18, 2014

I simply love this trail!! It has been the subject of so many fun stories and adventures like this one: This place has so much to offer and it is great all year around, I make it up here once per year!!!

Wednesday, June 11, 2014

Uphill trail that is fairly easy hike. About 15 minutes up you are allowed to camp and are currently allowed to have a fire. A buddy and I hiked in about 4 miles and camped over night was a good time and would do it again downhill was super easy!

mountain biking
Wednesday, June 20, 2012

Exit at University of Colorado Mountain research station, trail up ahead on right. This trail is very strenuous and 90% up hill, when heading north on trail. They call it north sourdough. Their are jagged rocks that cover whole trail all 6 miles up. It is fast down but beware, I am an advanced rider and my wrists killed me at the bottom and I'm on an all mountain bike. Little traffic also. Over all great ride, nice to get out city and hot temps and HIGH in the mountains :) 6/20/2012

mountain biking
Saturday, August 07, 2010

My Experience

I started the ride at the Sourdough Trailhead off Country Road 116. The trail was well marked, and I was eager to ride on this sunny day. Within 5 minutes I was puffing, panting and cursing the baby heads, but I kept going, telling myself things could only get better!!.. Well, things only got worse. The lose rocks combined with the root carpet was killing me, and I was having traction issues that forced me into higher gear, a gear that was slightly too high for this ride, and I was knackered with about 2.5 hours ahead of me. I kept my head high, assuring myself it was going to be worth every minute of the grunt. But it never came, after a 2 hour slaughter, I reached the turn around point.. now I knew for sure that I really did not like this trail, it was like riding on a dry creek. Yes, the ride back was much faster, about 40 min. but it was a hell of a bumpy ride, and I was lucky that I actually managed to stay on the bike.
This trail really confuses me, cos quite a few people recommended it, the books say it is the BEST singletrack in the Boulder area, and I read it was a very scenic trail.. ??? I, for the life of me cannot see what is appealing with this trail.. I am even seriously considering doing it again, just to see if I missed something along the way!!

Other Info:

Traffic on Trail : Two Mountain Bikers from Nebraska, and One Down Hiller walking his (very nice) bike
Wild Life : None
Scenery : None at all scenic (in Sept)
Other : This trail is like riding on a dry creek

My Trail Rating : 3 / 10

Trail Stats & Information

Nearby City: Ward
Length: 12.2 total miles
Trail Type: Out-and-Back
Skill Level: Technically moderate. Physically moderate to challenging
Duration: Advanced Riders, 2 2.5 hours; Intermediate Riders, 3 3.5 hours
Season: May to October
Trailhead Elev: 9200 feet
Top Elev: 1020 feet

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