I have a Trek 2000 road bike and an older model Trek mountian bike, 350 I beleave, with a ridged fork. I find I make about 3 mph less average speed on the mb even though it is outfitted with semi slick 1.25 inch tires. In the wind the speed difference is even more pronounced a difference because of the riding posistion. I also have a 7300 that my son rides and I have ridden it 25+ miles and can't see myself doing 50+ on it at all.