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North Sourdough and St. Vrain Loop

Very Difficult


5.4 mile 8.7 kilometer point to point
95% Singletrack
Very Difficult


Ascent: 641' 195 m
Descent: -650' -198 m
High: 10,244' 3,122 m
Low: 9,698' 2,956 m


Avg Grade: 5% (3°)
Max Grade: 15% (9°)


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Map Key

A 4.5 mile sustained technical loop from Brainard Lake entrance through lesser seen wilderness.

Kevin Stiffler

Electric Mountain Bikes Not Allowed

Features -none-

Occasional fire restrictions.


An amazing, lesser traveled trail that induces feelings of being in a backcountry setting. Enjoy meadows and technical singletrack that offers hard to come by views!

Sustained technical sections can make for a slower trail pace; there's certainly potential for hike-a-bike sections. Mind the weather at altitude.

Need to Know

This trail was added by Kevin Stiffler, who is a guide/trainer/expert for the best skills clinic business in Colorado! Check out: for more info about them.


From the Brainard Lake entrance, take North Sourdough on the right. The Sourdough Trail - Southern Half is located here on the left, with the entrance road to Brainard Lake splitting the trail in half.

Continue along North Sourdough for 1.2mi of fast, technical descending. Enjoy the breezy recovery of your descent because sustained technical climbing soon awaits.

After 1.2mi, turn Left onto South Saint Vrain Trail trail. Follow for 2.0mi and begin working through some of the most difficult climbing sections. Enjoy the babbling brook and dense forest here. Cross the stream and continue climbing to a mountain prairie. Keep your eyes open for wildlife in this wet prairie, but be sure to keep your tires on the narrow wooden bridges!

After 2.0mi, turn Left again onto a .5mi connecting trail towards Waldrop Trail, cross through some more wetlands and climb back into the forest. Shortly thereafter, you'll be greeted by some fast, flowy and smoothness on the Waldrop Trail for the final 1.5mi back to the Trailhead at the Brainard Lake Entrance Parking Lot.

This is a great addition to Sourdough Trail - Southern Half to increase difficulty and work on technical skills.

Biked this trail?

We need help with the following missing trail information:

Family Friendly, ADA Accessible, Dogs Allowed, Features, History & Background


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Jul 5, 2019
Tata Ridesalot
Aug 17, 2018
dave van tol
Rode this in the opposite direction than shown on the map, plus a lap around Wapiti. Waldrop is definitely not fast and flowy when riding it uphill!
Oct 28, 2016
Raúl Gross
Rode clockwise. Very technical. Lots of challenging watermelon patches to ride through.
Sep 17, 2016
Sam Gosney

Trail Ratings

  2.5 from 2 votes


  2.5 from 2 votes
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in Colorado


28 Views Last Month
3,037 Since Jul 29, 2014
Very Difficult



Rocky approach to stream crossing.
Jul 23, 2019 near Nederland, CO
One of many wooden skinny bridge features- riding over this shorter one with ease.
Jul 29, 2014 near Nederland, CO
Scope out your line choice on this first stream crossing.
Jul 29, 2014 near Nederland, CO
Looking forward to the smooth flowy section.
Jul 29, 2014 near Nederland, CO


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