Expect to walk more than ride until the trail gets significant maintenance. If you encounter better conditions, please update the GPS track and the description so that others can enjoy this trail.
Sumac Creek Trail doesn't get the traffic of the more popular trails in the Bear Creek Area to the south—just getting to the trailhead on West Cowpen Road (FS Road #17)
can be an adventure in a passenger car or low clearance vehicle. This leaves it often in need of maintenance, which is a shame because it was built for mountain biking in the late 1990's.
The trail connects a number of older roadbeds with singletrack forming what should be a trailbed with nice flow along the ridge to the south of Sumac Creek. There is a nice creek crossing about 2.0 miles into the ride. At the 3.0 mile mark, the trail intersects with Lacky Knob Road (FS Road #630C)
Nominally, the Sumac Creek Trail continues to the west, but I found this section completely overgrown and covered in fallen trees—essentially impassable—in summer 2018. There should also be also be a bailout trail, Sumac Creek Spur #217A, just after this intersection but it is barely discernible and even less passable than the continuation of Sumac Creek Trail.
Sumac Creek Trail should continue an additional 4 miles or so, crossing Sumac Creek a second time and then ending at Pleasant Gap Road (FS Road #17A) to take you back to the trailhead.