You can pick up the Cape's premier bike path, the 25-mile Cape Cod Rail Trail (www.mass.gov/dcr), at several points. In fact, riding the entire trail in one day doesn't do justice to its sights and side trips (though it certainly can be done). Many cyclists, especially those with small kids, prefer the piecemeal method because they can relax and enjoy the sights—and not turn their legs into jelly.
The trail starts at the parking lot off Route 134 south of U.S. 6, near Theophilus Smith Road in South Dennis, and it ends at the post office in South Wellfleet. Access points in Brewster are Long Pond Road, Underpass Road, and Nickerson State Park. There's also a spur off the trail that goes to Chatham.
The ride in Dennis starts as a flat, straight spin through a small pine forest—a good warm-up exercise. Your first road crossing is at busy Great Western Road, one of the town's major thoroughfares, after which you'll pass Sand Pond and Flax Pond in Harwich. The Dennis part of the trail is short, but it's worth starting here for the ample parking at the trail's entrance and for the several bike-rental places that set up shop on Route 134.
A guidebook published by the Dennis Chamber of Commerce includes bike tours and maps. You can rent bikes from a number of places along the Cape Cod Rail Trail.
Barbara's Bike Shop. Barbara's Bike Shop is at the rail trail entrance, the closest of several local shops that rent bikes. Prices start from $24 per day (with hourly rentals available as well). 430 Rte. 134, South Dennis, MA, 02660. 508/760–4723. www.barbsbikeshop.com.