I am wanting to go on a cross-country ride this summer. I currently ride around 20 miles a day pretty darn easily. (but without any gear). I am riding a Trek 6500 mtn. bike. I plan on buying some "slicks" and a BOB. But what I am wondering is do I need a "touring bike". I mean, I have ridden 50 miles in a day without any problems in comfort. What about different gearing so I can go faster?