Harlem Valley Rail Trail is potentially one of the longest bike trail in upstate New York. I say potentially because it is mapped for about 46 miles between Chatham and Wassaic, some portions being finished but most of that being in an exploratory state waiting for the funds to be be disbursed. The bike path is a rail trail being developed on the old rails of the Chatham-Dover Plains train tracks.
The paved trail starts in Hillsdale and goes for about 2 miles ending in Route 22. From there you have to follow the road for about several miles and turn left to Old Farm Road that brings you to the second portion of the paved trail, a section of about 5 miles that goes through farms and corn fields. Close to its starting point, you can turn off to an area of Taconic State Park that preserves inside one of the old iron-works decommissioned in 1904 for which the area used to be known. The old iron mine is now a local pool and the church of St John in the Wilderness was established for the people working in Irondale.
After that the bike path continuous on Route 22 for about 10 miles and reaches Millerton, a charming village from where the trail is fully and continuously paved going for about 10 miles to Amenia and ending at the Wassaic Metro North station. The easy access to the trail coming from the South is through I-684 continuing on Route 22N.