Randochap said:
Not necessarily.
I just got in from a 35 mile spin on
my Bleriot. I am running 42mm tyres @ 60psi on it. They float over chip seal like a wind-driven cloud. I pulled away from my mate (on 700X27) on a particularly bumpy section. I was 100 yards in front of him in a mo.
Hard tyres on bumpy surfaces actually slow forward movement; in other words,
increasing rolling resistance.
This is a strange one indeed.
On a surface with a LOT of texture, eg a chipstone road, a rock hard tyre will be continuously rolling against small hills due to the micro ( small anyway ) differences between the roughness of the surface.
A wider, softer tyre will absorb the differences and roll along as if it was a flat surface.
The immediate thought on this is "Harder is less Crr", which is true on a track or smooth tarmac road ( especially laid for big events ) and most roads in the UK and USA ( I cannot speak for Canada except for Quebec and Halifax which are a couple of thousand miles from Randochap ).
Where the grit is peculiarly large or broken up, the rolling is worse on hard tyres.
I ride 26 x 1 3/8" in winter and a rough section of my commute is smoother on this bike than my Giro 500 ( which seems to slow-up ).
On vibration. When you assess where the rough raod is, stand up slightly to let your legs take the vibration and hold the bars gently. There are gloves on the market for Hammer Drill operators etc.
My take on this is 'there are many more miles of smooth road, a few miles of rough are tolerated, so I ride on rock hard tyres to gain an overall advantage'.
