Two days enough time or Pittsburgh to Cumberland for someone that is out of shape? Definitely not.

Don't let the fact that the trail is flat fool you. The trail surface will provide significant rolling resistance.

Also what is your hurry? You are coming from Cleveland to just buzz the GAP? Why not just ride the Ohio & Erie a couple of times?

I don't understand why anyone would want to punish themselves riding a single speed but to each his own I guess.