Ivar Hesselager said:"The discussion about the differences in rolling resistance between
23-25mm tires is somewhat theoretical.Practically you recognize the better damping and cornering characteristics
of the 25mm tire.By experience I can tell you that you won´t be any slower with a 25mm tire
but have a more enjoyable ride if you prefer to go on backroads or even
try some field roads.Wolf vorm Walde
Product Manager Bicycle Tires"Thank you for that opinion. I will still be looking for facts.
I trust, that if mr Walde knew of ane measurable difference, he would be
willing to tell me about it. Therefore he and Continental Tires don't know
of a difference. And if they don't know, most likely nobody knows. I find
that surprising and interesting.
That's not my interpretation of his response, but you could be right.
My take on it is that he's saying it's complicated, that multiple
variables play into rolling resistance, but that you will have a more
comfortable ride with no loss of speed if you are riding on relatively
rough pavement.
I cannot believe that Conti does not have a setup for getting some
measurement of RR for its bicycle tires. Whatever number they get, it
might be only meaningful for the exact environmnet- the test setup-
where it was produced. I can understand their reluctance to give a hard
number that would be immediately used by the riding public to draw
conclusions that are often invalid.
Quoted message said:It is obvious that if you give priority to comfort and tracking, you
should prefer af 25 mm to a 23 mm.
Quoted message said:But even if you give priority to speed, the 25 mm tire appears to be the
better choice. But nobody knows.
I would say it depends on the road surface and speed at which you ride.
Quoted message said:Here is an uncovered field for an engineer student or for a bicycle
magazine to look in to.
Could be interesting to see how rolling resistance varies by air
pressure, road surface, tire construction- a lot of variables to deal
with. That's why I think that Conti's answer was more precise than it
might seem at first. He basically boils down the multiple variables to
a meaningful answer: for the conditions he describes, you will be more
comfortable and just as fast with a 25mm tire. There is an implication
that for other conditions the answer could be different.