20.85 km 68390.78 feet 12.95 mi 7351.00 seconds 122.52 minutes 2.04 hours 6.34 mi/hr
The second of two rides last Saturday, I rode the South County Trailway, or at least the southern portion of it. It runs from the Bronx through Van Cortlandt track on the Old Put (Putnam Branch of the New York Central). Through the park, it's an undeveloped trail. People have made a herd path off to one side of the ties, which are still there.
At the Westchester County line, it starts being a paved trail. Both have their charms. It continues for a few miles north of Tibbett's Creek Park, then runs into a section that they're working on right now. Beyond that it may be walkable (I saw people walking on it), but it's not rideable.
Further to the north, it looks like the South County Trailway becomes paved again, all the way up to the North County Trailway.