Dirty Bismark Loop
On Coalton Trail, Louisville, Boulder County, Colorado
Dirt Route
14.04 mi
Length
932 ft
Elev gain
942 ft
Elev loss
5,958 ft
Max elevation
dirt 51%
gravel 49%
other 0%
pavement 0%
Elevation Click the profile for Street View
The Dirty Bismark follows the dirt version of the old Bismark road bike loop - this one has a mix of gravel roads, easy singletrack, and gravel paths.
2 votes
on November 21, 2021
A favorite! I do agree with Aaron on the rougher parts. I really enjoy the challenge on 38s but it's hard to recommend it as "gravel" on some of those sections.
on June 7, 2020
There are western sections of this loop that are not typical gravel bike friendly. I ride this weekly and almost never do it on a CX bike even with 38mm tires. Much of it is a blast but sections are slow going on a gravel bike. Baby head rocks and a few drops.