MTB Project Logo

Dirty Bismark

 3.4 (153)
Zoom in to see details
Map Key

15.7 Miles 25.3 Kilometers



941' 287 m


-939' -286 m



Avg Grade (1°)


Max Grade (9°)

5,953' 1,814 m


5,523' 1,683 m


Shared By Michael Ahnemann


All Clear 22 hours ago
Dry History

Getting forecast...

A fun Boulder area cruise following the famous Morgul Bismarck road course.

Michael Ahnemann

Dogs Leashed

Features -none-


This ride follows the well-known Morgul Bismarck road cycling route - a famous race stage in the 70's and 80's.

The trails are easily accessible from Boulder, Superior, and neighboring towns, and it's mostly smooth with just a few slightly technical spots. It's just challenging enough to keep advanced riders interested, but rideable by just about everyone. This makes it a popular route, and it's often rideable almost all year.

Need to Know

There are several trailheads along this route, so start wherever it's convenient. You can also cross over Route 93 in a couple of places to ride more of the Marshall Mesa trail system. A great spot to do this is at the Greenbelt Plateau parking area to add on the west half of the Spring Brook Loop for an additional 8.3 miles and more singletrack.


The trail as marked here starts and ends at the Marshall Mesa trailhead, which is the largest trailhead along the trail, closest to Boulder. From the trailhead, you'll head onto the Marshall Valley Trail, which is mostly flat with a short solid-rock playground thrown in.

The trail soon crosses a bridge and meets up with Cowdrey Draw and Community Ditch trails. Take a left onto Cowdrey Draw and you'll head mostly downhill on singletrack, popping out at 66th Street.

Continue through the gate and across the road and you'll now be on the Mayhoffer-Singletree extension trail, heading towards Superior. This section twists back and forth on itself and climbs just a bit. It's a serene, rural part of the ride - you're likely to see horses or cows along the way, and it feels like you're farther away from the neighboring roads than you are.

Next you'll meet up with the Meadowlark Trail, which climbs a bit, right next to an office building. The rural feel will go away for a bit until you head away from the office building and back towards a reservoir. Then the trail heads south next to McCaslin Blvd. until you reach the Coalton Trailhead.

This section of trail (Coalton Trail) l is mostly dirt road, and it gets you to the top of Marshall Mesa. Keep going until you reach yet another small trailhead to meet up with the High Plains trail.

Follow the High Plains trail, which is singletrack with a few mildly technical rocky sections. You'll eventually reach the Greenbelt Plateau trailhead where you can either cross Route 93 to meet up with the rest of the Marshall Mesa trails, or continue along this ride back towards the start.

Continuing along this ride, you'll end up on the High Plains Trail, which is singletrack, with a few mildly technical rocky sections. From here, turn right onto Greenbelt Plateau Trail and climb this mellow, mostly smooth section of trail. After the trail starts back downhill, take a right turn over a couple of log stairs, then down a bit more to some more log stairs and a short technical rocky bit, and over a bridge to cross the irrigation ditch.

Turn left onto the Community Ditch trail heading west, and ride until you reach Route 93. Here, you have another option to cross 93 and ride the Marshall Mesa trails to the west. But to get back to the trailhead, take a right onto Coal Seam.

Coal Seam is mostly downhill back to the trailhead, and somewhat technical, with twists and turns and rocks to keep things interesting. Ride the final rock garden, or ride around it, and you'll be back where you started.

History & Background

The Morgul Bismarck is a relatively famous stage from the Red Zinger / Coors Classic road cycling race from the 1970's and 1980's. Over time, trails along the perimeter of this classic road route have been built, making the Dirty Bismarck MTB trail.


You & This Featured Ride

Rate Quality

   Clear Rating

Rate Difficulty

Share This Ride

Your Check-Ins


Mar 24, 2019
Trevor Lopez
Nice and dry. 15.5mi — 2h 12m
Mar 23, 2019
Taran Warthman
Mar 23, 2019
Keaton Noon
Dec 16, 2018
Gary Thornberry
Dec 15, 2018
Jenny Trawick
Enjoyed the first half. After the last big incline it was VERY windy at the top. Lots of unleashed dogs at the end too. 15.7mi
Dec 15, 2018
Kegan Warring
Dec 14, 2018
J Adams
Dec 8, 2018
combined with spring brook loop for 24 mi.

Stewarded By

Trail Ratings

  3.4 from 153 votes


  3.4 from 153 votes
5 Star
4 Star
3 Star
2 Star
1 Star


in Colorado


273 Views Last Month
32,500 Since Mar 21, 2013
Easy/Intermediate Easy/Intermediate

Sandor Dornbush
San Francisco, CA
Sandor Dornbush   San Francisco, CA
Jason it is definitely CX ridable. That is my preference and I think the only way to put up really competitive times. May 30, 2018
Matt Parsons
Denver, CO
Matt Parsons   Denver, CO
I just rode this on my gravel bike with 40mm WTB Nano tires. It's a lot of fun, but there are some rocky sections that are really difficult. I can imagine having a lot more fun with some beefier tires or suspension. Jun 15, 2018
Ken Carignan
Boulder, CO
Ken Carignan   Boulder, CO
This trail is fine for CX. There's just a one minute section somewhere on the west end, with unavoidable rocks that you'll want to take slow to avoid a flat. 90% of the trail otherwise is typical gravel and dirt single track. The return to the trailhead has a few small 1' drops and technical mountain bike section that you'll be fine to blast through dodging all big rocks with basic MTB handling skills. Bring a spare tube for sure. Sep 8, 2018

MTB Project is part of the REI Co-op family,
where a life outdoors is a life well lived.

Shop REI Mountain Bike

MTB Project is supported by

Support Your Local IMBA Chapter