Rugger from Arlington, VA on 6/3/2014 12:27:55 PM:
Consider DRIVING your bike and equipment to Cumberland, then driving back to DC, leaving your car at the airport, taking the subway to Union Station, and then taking the train to Cumberland. I did this, only just went as far as Harper's Ferry, spent day/night there, then rode back to DC/the airport over a three day period, stopping along the way, camping on the C&O. As to how much you can travel each day, a loaded bike is a LOT slower than a casual weekend ride, and the bike trail west of Great Falls gets more and more rough, and 20 miles west of Georgetown is overgrown with roots, grass, rutted. I did well making thirty miles a day.