Old Trench Road #181 is actually singletrack. It began as a line for erosion control and then has been reclaimed by nature over the years.
The route starts by dropping in from Ridge Trail #157
and then mellows out into a nice traverse. Through here, you'll be pedaling through aspens and open meadows with nice views of the surrounding peaks.
As the trail rounds a ridge, it starts a steady downhill to Holman Trail #039
. From here, you'll have two options, both very steep and technical descents. Continue on Holman Trail #039
for a short section and then stay left on Holman Ridge - Cabin Flat #172
to access Mill Canyon #40
Stay on Holman Trail #039
for a very rowdy and rough adventure to FR 085.