This 4 mile trail has a lot of easy sections on it. It is a dirt path that follows an old rail between Bedford and Concord and makes several street crossings. At one time you were able to include the Great Meadows loop in the ride, but bikes are no longer allowed on that section. It still might be worth you while to stop at Great Meadows and walk the loop.
Off the trail option
Early in the ride you can go off the main path into the woods. There you will find muddy ATV tracks. Weave through these tracks and you will eventually come to the edge of Hanscom airstrip. This area is much more technical than the regular trail.
The Farm Field
After crossing a private (paved) farm road, you ride along the edge of one of the fields.
Side trail to Sleepy Hollow
Turn right after the granite marker on the left side of the trail (easy to miss). The trail is not too rough except for a lot of tree roots. When you arrive at the cemetery, there is a pond on the left. You can continue on the road bearing to the left to get to the authors ridge (burial sites for Alcott, Thoreau, Emerson).