I ride my Gary Fisher hard tail on black top for my 34 mile RT. I have knobbies to make the ride more challenging and to sustain my fitness level. I could ride my road bike or my cross bike but they are both way to light and don't provide me the workout that I enjoy with my 45 pounder. Maybe one day when I get old (I'm 53) I'll change and put slicks on the mtn bike. :-)

Ride safe,

Jeff