Originally Posted by lindafranc

I recently changed from 700 x 35 mm semi-slicks to 700 x 41 (or so) heavy treaded tires. I initially found the new tires much harder to pedal, maybe like 30 to 40% harder. It was kind of like lifting weights, not huffing and puffing. My legs kind of burned and it was not fun going up hills.

Then I checked the tire pressure and it was 25! So I pumped them up to near 80 (the max indicated on the tire) and they now feel only slightly harder to pedal than the 35 mm semi-slicks. I have only went on three 4 mile rides so I don't know for sure if it is in fact true. Has anyone experienced this? Does tire pressure make a major difference?