The Gazette published a story in it's open forum section by a woman who rode the C&O after taking the red line to Shady Grove.
My bicycle and I took Metro’s Red Line to Shady Grove, a mysterious place I’d heard of many times (as in ‘‘This train’s final destination is Shady Grove”) but never seen. Turns out, it’s not that exciting, unless strip malls are your thing. But I left the Metro station and headed west on roads that my map indicated were bike-friendly, and gradually commercial areas gave way to farms and small hamlets.
I've been thinking of doing something similar myself, riding out to the end of each Metro line and then biking back. Just to do something different.