This is an excellent loop that covers a bunch of the best Southern Montgomery County singletrack. The terrain is relatively gentle packed clay and dirt with some solid climbs and a few stream crossings and some fun swoopy descents. Nothing overly technical perhaps with the exception of a fifty foot stream crossing, but it is easier than it looks.. Also featured: the historic Black Rock Mill and a segment including the C&O Canal with some great views of northern Virginia.
To do the entire loop, park at Quince Orchard High School. This will allow you to break up the major paved section of this ride to the beginning and the end. Take a left out of the lot to ride down Rt. 28 until you see a trailhead on your right. Traffic here can be busy so be careful! Turn right onto the Muddy Branch trail and ride this over several road crossings until you hit Esworthy Road.
Take a right onto Esworthy, over the bridge and ride approximately 400m uphill until you see another trailhead to your left. Enter there and continue on the Muddy Branch trail until you hit another road crossing. Here, cross the road and enter the parking lot facing you. Continue on the Muddy Branch trail in the rear left-hand corner of the lot. Follow this trail down a ripping descent (but watch out for horse poop!) until you hit a grassy clearing. Take a right turn here and find the continuation of the trail in the very back of the field.
Ride through until you hit a canal and parking lot. Follow the parking lot until you hit a gate and bridge to cross the canal; cross here and take a right turn on the canal towpath. Lockout your suspension and cruise for the next few miles until you pass Victoria's Lock and subsequently get to Riley's Lock. Cross the bridge over Seneca Creek and take your next left-hand turn onto a windy grass doubletrack path. Ride out here until you hit River Road. From here, take a right onto River Road and an immediate left onto Old River Road. Ride a little past the white general store to find the trailhead for Seneca Bluffs on your right-hand side. From here, cruise down a fun, hilly, generally buffed out trail until you see a large stream crossing. Ride through the stream (or hike a bike if you prefer) and continue riding until you hit Route 28.
From here, take a right-hand turn, cross the bridge, and then take a left into the parking lot on the other side of Rt 28. Enter the trailhead on the right to continue on Seneca Bluffs, riding through to Black Rock Road. From here, you can either continue on the route by simply crossing the road to Seneca Ridge Trail
or you can add on some singletrack mileage by crossing the bridge and taking the Seneca Connector
to Schaeffer Farms Grand Tour
. There is an awesome system up this way and you could easily add on several miles of fun, fast singletrack. When you're done, ride down the (super sweet) pump track labeled "Experts Only," and return to Black Rock Road. Continue on the fun and flowy Seneca Ridge Trail
all the way through until you hit Riffle Ford Rd (a 2 lane road with very large shoulders). From here, hit the lockout again and cruise up the hill until you hit Rt 28. Take a left onto Rt 28 and find the originating HS parking lot on your right.