This article was co-authored by Patrick Miller and myself to promote local epic mountain bike rides in our region (Maryland/DC/Virginia) without having to travel big distances by car. It was published in the M.O.R.E. newsletter and now has a permanent home on their web site. At it's core is an overview of the Tour de Patapsco ride. I've since put together a more comprehensive guide to the Tour de Patapsco here on Single Speed Outlaw. It will give you plenty of detail so you can navigate the existing trail systems from Avalon to McKeldin including the portions of the Patapsco Thru Trail that are completed. Read both articles, pack a lot of water and a lunch, and go build your own local mountain bike adventure ride right outside of Washington DC and Baltimore.