Thanks for a great variation of insights and interesting considerations.
But it still remains a mystery that there is no available messurements of
rolling resistance from 22 mm respectively 25 mm tires with their
recommended airpressure.
I do undertand that the answer to a simple question may be complicated
and will depend on numerous circumstances on the real road.
And I do understand that a reduced RR should be seen in relation to
higher wind drag and weight. And I do understand, that all these factors
have so little impact that it is tempting to end the discussion with the
conclusion: It don't mean [censored].
But I am still curious and I still find the question relevant: In the
spring of 2003 the Belgian rider Van Petegem won the Tour of Flandern as
well as the Paris-Robaix on 25 mm Continental Competition tires. He must
have trusted, that those tires were faster than narrower ones. Did he
guess or did he know?
Whether you are racing to win or racing to make it through within the time
limit, you want the facts that will help you choose the right equipment.
The surprising conlusion, that the wider tire has lower rolling
resistance, is based on tests of tires of identical construction and
identical pressure. The explanation that is given is, that the two tires
have a contact area of exactly the same size, but the wider tire has a
shorter and wider one, which produces less RR than the narrower and longer
contact area.
If the result of that test is interesting, then it is even more
interesting to make a test of the same two tires with the recommended tire
pressure in each.
I think the Continental production manager was well aware, that I didn't
just want an advice on what tire to choose for my bike. I can´t think of
a reason not to give me an exact answer if he knew it. He would not
reveal production secrets by saying: â€We have made the test, it shows that
the wider tire has a 10 pct. lower RR†– or the opposite. But that is at
matter of interpretation, I admit.
Ivar of Denmark