Road bicyclists use slick tires for speed. The tires on road bicycles come in quite a variety, but most are ultra-light and offer very little suspension, flat protection, or traction, really, especially at speeds over 30mph. They are made purely to maximize speed and efficiency. I love road cycling, but I don't think I'd want to run a motor kit on a road bicycle with skinny tires. A cyclocross bike seems doable, and I'm working on it now. I liked running road slicks on my mb (26x 1.75) but got flats a lot and couldn't go down country roads easily.