July 2, 2014
I rode the eastern portion of Difficult Run in Spring 2014 before all of the trees and brush grew in. Because it was so bare at the time, it was a lot easier to look ahead for obstacles and ride faster. Now (Summer 2014) with all the growth and other folks on the trail you have to be a bit careful when attempting to get your speed above 10pmh (in certain sections). Overall, I liked the entire ride but unless you're familiar with the trail, you may not realize that the trail actually continues all the way to the Potomac River (beyond the parking lot on Georgetown Pike). The trailhead for the eastern portion of the Difficult Run trail picks up where Colvin Run crosses Leesburg Pike. I'd be interested to find out if anyone has ever attempted to ride their bike across the rock bridge where it appears to be too deep to ride in the water.
Terrain encountered: Pavement, hard-packed dirt, gravel, sand, and watermelon-sized rocks (half-buried).
Obstacles encountered: Walk-your-bike water-crossings, tree roots (love 'em), dried creek beds, half buried culvert pipes, over-grown brush, brush w/ thorns, and fallen trees (fairly large).
Sections of the trail were as wide as four to five feet and other portions were as narrow as one foot wide.