Dirty Bismark

Trail

Dirty Bismark

Location: Colorado, United States, North America

Lat/Lon: 39.94133°N / 105.19821°W

Trail Type: Cross Country, Paved

County: Boulder

Technical Difficulty: Easy

Aerobic Difficulty: Medium

Layout: Loop

Elevation Gain: 630 ft / 192 m

Length: 14.8 Mi / 23.8 Km

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Page By: Chris

Created/Edited: Oct 11, 2007 / Oct 2, 2008

Object ID: 262228

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Table of Contents

Overview

The "Dirty Bismark" is the name given to the dirt version of the uber-classic road ride, the Morgul-Bismark. The Morgul-Bismark was a famous stage in the now-defunct Coors Classic stage race that took place in the 70s and 80s.

The route for the road race started and finished at the top of "The Wall"...a steep climb at the southern end of McCaslin Blvd. From there it went west on CO Hwy 128 to Hwy 93. It continued north on Hwy 93 to Hwy 157 where it went right and back east to McCaslin. A right turn on McCaslin took you up "the hump"... a very short and steep climb and then back to the base of "The Wall".

The dirt version approximates this loop on singletrack, doubletrack, dirt roads, and a short stretch of paved road (McCaslin). It's a fairly non-technical ride, but offers stellar views of the Front Range and a great workout.

Trail Description

This description starts and finishes at the Marshall Mesa trailhead at the corner of Hwy 93 and Hwy 157. There are numerous points from which to access this trail, they are noted in italics. The route is given in a clockwise direction simply because the orginal Morgul-Bismark went clockwise... it's a great route either way.

Marshall Mesa Trailhead
From the Marshall Mesa trailhead, follow the Marshall Draw trail east for 0.9 miles. You'll come to a small bridge and intersection. The trail curves uphill and continues east meeting the Community Ditch trail at 1.0 mile... go left. You'll immediately reach the Cowdry Draw trail. Follow this east to 66th Street (paved) at 2.0 miles.

Cowdry Draw Trailhead
Turn right and follow 66th Street. It turns to gravel, then dirt as you pass an atmospheric research center on the left and the old Marshall landfill on the right. The road curves left and quickly and steeply drops down to the intersection with Coal Creek road at mile 3.4. Go left on Coal Creek and follow this gravel road to mile 4.7 where you'll reach the Singletree Trail. Take a right and follow the Singletree trail across Coal Creek to it's end at mile 5.5.

Singletree Trailhead (Superior)
Continue on the gravel road to mile 5.7 and curve right, past the abandoned house, and out onto McCaslin Blvd at mile 5.8. Turn right and follow McCaslin up the steep hill and down the other side. Just past the entrance to the condos on the right (mile 6.7), take a right on the dirt service road (mile 6.8) and parallel McCaslin down to the light.

Coalton Trailhead
At the light (mile 7.3) turn right, cross the gate, and follow the Coalton Trail west to the top of the hill at mile 8.3. The views from here are awesome. Turn left and follow the Coalton trail for another 1.8 miles to the end of the trail at mile 10.1.

Hwy 128/High Plains/Coalton Trailhead
Bear left on the newly created, IMBA designed High Plains trail. This is the best part of the ride... 2.5 miles of great singletrack that winds down to the Greenbelt Plateau trailhead at Hwy 128 and Hwy 93, and mile point 12.5.

Greenbelt Plateau Trailhead
From here, take the wide doubletrack Greenbelt Plateau trail north, up the climb. You'll crest the top of the climb around mile 13.3 and descend down the other side. At mile 13.7 bear right onto the the Marshall Mesa trail. Follow this for 0.2 miles down to the intersection of the Community Ditch trail (just past the bridge) at mile 13.9. Bear left on the Community Ditch trail and follow it west for 0.4 miles to Hwy 93 at mile 14.3. Turn right and descend the Coal Seam Trail for 0.5 miles back to the trailhead, and the finish of the ride, at mile 14.8.

Mileage Points:
--------------------
0.0 - Marshall Mesa Trailhead
0.9 - Bridge, cross and climb the hill bearing east
1.0 - Community Ditch trail, left turn
2.0 - S 66th St, right turn
3.4 - Coal Creek Rd, bear left
4.7 - Singletree Trail, turn right
5.5 - Singletree Trailhead, trail ends, straight on gravel
5.7 - Right then left, climb to McCaslin
5.8 - Right on McCaslin, climb the Hump
6.7 - Condo Entrance
6.8 - Dirt service road, ride this to avoid McCaslin
7.3 - Stoplight, Coalton road and trailhead. Right on Coalton Trail.
8.3 - Top of climb on the Coalton trail. Trail bears left.
10.1 - End of Coalton Trail - Hwy 128, bear right onto High Plains Trail
12.5 - Greenbelt Plateau trailhead, right on wide doubletrack
13.3 - Top of climb
13.7 - Marshall Trail, bear right
13.9 - Community Ditch trail, left turn
14.3 - Coal Seam trail (at Hwy 93), turn right and descend
14.8 - Trailhead

Getting There

From Boulder (Canyon and Broadway):
Go south out of Boulder on Hwy 93. You'll leave town and cross some open space, eventually coming to a light at Hwy 157 (Eldorado Springs Rd). Take a left here and then take an immediate right into the trailhead parking area.

When to Bike

This route is ridable year-round and makes a good winter ride when the high trails are buried in snow. Watch for rattlesnakes during the summer months.