Dirty Bismark route

Leashed dogs welcome. Unleashed dogs with City of Boulder Voice & Sight tags welcome on some trails. Please follow signage posted at gates.

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 all year long.

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 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) is mostly rocky, steep and loose 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, turn right onto Greenbelt Plateau Trail and climb this mellow, mostly smooth dirt road. After the trail starts back downhill, take a right turn down a couple of log stairs (or the trail next to them), 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 under 93 and ride the Marshall Mesa trails to the west. But to get back to the trailhead, take a sharp 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.