It's primarily 2 track on the C&O, which is half the trip Some areas will beat you up on a MTB, some are like riding on packed ground. 25 miles can be detoured onto a 25mi flat rail trail if desired (WMRT) Mud, rocks, tree roots not uncommon. Tour's scheduled early enough in the wear that you'll be dealing with what the vagaries of the winter bring.

Most generally accepted "perfect" bike is a cyclocross or hardtail MTB. Of course, like anything, there are those that will ride it on a road bike and 23's and scoff, just as there that will whine the whole way on a FS MTB that it's too rough. Reality is somewhere in between.

I'm not saying that a 'bent can't be ridden on it. It's just that it's the exception rather than the rule. That may be the riders that ride them, it may be the condition of the trail. It may be a combination of the both. I rode the GAP/C&O in April 2008, the GAP was soft and wet and a PITA to ride and the C&O was a mud pit. But in looking at Historian's post, he says he's not a strong rider on a regular bike, and has medical issues. I personally think that buying a 'bent in the early part of the year and expecting to be ready for a tour on what could potentially be a messy trail is a bit aggressive. I hope he can, I hope he's happy, and I wish him well. There are times I'm wrong and I'm hoping this will be one of them!

-R