A popular choice for distance bicycling in Baltimore is Pretty Boy Reservior, but most riders turn away from Pennsylvania after crossing the reservior, and head back to Baltimore. May I suggest turning left on Middleton road, in order to take in the hilly roads in Pennsylvania. Using this route, I was able to log over 5000 ft of uphills in almost 80 miles.
… and some photos. The Pennsylvania border on Middleton road is quite different from what you see in areas closer to Gettysburg.
Michael L. Love
This scene from Falls Road Station was just a little too precious. Maryland.