I have a comfort bike with 26x1.95 tires, which are smooth on the surface that makes contact with road, but knobby on the edges. I was wondering if I put 26x1.5 slick tires on if I would get much increase in speed/performance. I've heard different stories from different LBS's. One told me the difference would be noticeable, another said it would be a waste of money since the difference wouldn't be significant. Has anyone done this? Did it make any difference?