Just got back from the GAP, which was a lovely ride -- you could do it on a road bike. But we did a few miles along the C&O at the end, and the quality of the ride went down straight away. The gravel is chunkier, and there were stretches of mud/dirt/dust which could have been horrible in the wrong weather conditions. We met people who had come from Washington along C&O, and they said it was so muddy that the fenders glued themselves to the tires with all the extra mud. Yeek.

I could certainly have done the GAP part of the ride on my folder, which has the widest tires you can fit with road bike brakes (I think they are 1-3/8). But I think it was much more fun and more comfortable on the hybrid I used. I fitted Continental Travel Contact tires, which were absolutely perfect -- they have a slick tread, and knobbies on the rim, and I got no flats. We did not camp, and stayed in hotels and B+Bs along the way (steer clear of Dawson).

If you have time (and are interested), make a detour up to Frank Lloyd Wright's Fallingwater when you get to Ohiopyle. It's worth the climb.

I blogged about it here.

http://www.crazyguyonabike.com/doc/jhggap