/me is with Sideshowbob on this one. In fact, I'll go one further. I know of lots of single trails where a dirt bike barely fits between the trees and cliff. Quad simply can't go there.
Quads are fun, but to say a 400-800 pound machine 3 to 4 feet wide can go places a 150-300 pounds 2-wheeler can go makes me chuckle. Hell, I can pick up my bike and carry it over stuff. But of course, I ride a little dirt tiddler...
Random pic of my dirt tiddler when it was clean:
Chris H.