Do they exist and would they do me any good if they did? I participated in a trail ride with my Boy Scout Troop this weekend. I was riding my vintage 10-speed road bike with road tires. This was on the C&O Canal (for those unfamiliar with this ride, the part of the canal that we were on parallels the Potomac, and you ride on what used to be the path that mules walked on to pull canal boats). Flat and smooth for the most part, but many tree roots and sticks. I was the only one I saw the entire time with a bike like mine. Almost everyone else had mountain bikes. One of the other adults had what could best be described as a "first generation" mountain bike with a standard road-type frame with no suspension and 700C knobby tires. I was able to do the ride, but every tree root was jarring, and I nearly lost my balance in muddy spots. Even if I could find 27" knobby tires, would they do me any good?
Kirk Frameworks JKS-C, Serotta Nova, Gazelle AB-Frame, Fuji Team Issue, Schwinn Crosscut, All-City Space Horse
Fritz - I've been wondering the same thing (if they even exist) and have yet to find any. I've thought about putting 700c wheels on my 27" schwinn and going with cyclocross tires, but finding a suitable braking setup has so far been slowing me down. That and the schwinn's rear dropouts are 126mm and new 700c wheels are usually 130mm spaced for the rear. The cost of going through all of that is most likely more than it's worth.
I have a set of Kenda knobbys I keep on a back up/snow day wheel set for my commuter(s). They are 27 x 1 1/4 and ride ok. I have not tried to off road them other than through a constuction site and dirt accsess road. I assume they will get used in snow this winter. I have ridden them some on the road and they are loud and slow like knobbys will be.