Originally Posted by
6StringJazzer
If the carcass is flexing more, doesn't that increase rolling resistance?
Depends very much on the design of the tire. A tire with supple sidewalls create less rolling resistance than one with stiff sidewalls.
And let’s not forget the influence off the surface you ride on.
If you have infinitely hard tires, then anything you hit, you have to roll up-and-over. And that upwards motion steals some forward movement. A softer tire allows minor irregularities to sink into the tire instead, preserving forward motion better