Ivar Hesselager said:I thougt that makers of bicycle tires would have experimentally or
scientifically based knowledge as a foundation of their production.
Therefore I directed my question about rolling resistance to
Continental Tires
- and the production manager kindly sent me a reply that is surprisning
as well as interesing.
The question was:It has been experimentally established that a 25 mm tire produces less
rolling resistance than a 23 mm tire of the same model, and with
identical pressure.
But how does a comparison between the two tires i.e. 25 and 23 mm -
each with the recommended pressure (6,5 bar resp. 7.5 bar) come out?This will be the relevant comparison if you give SPEED priority to
comfort and tracking.
Nobody in this newsgroup of bicycle connoisseurs had been able to
deliver an answer to my question, but a few indicated, that the
difference in RR between the two tires would be very small and the
answer thus unimportant.That did not satisfy my curiousity however, so I sent the question to
Continental Tires - since it is their 4-Seasons 25 mm I have chosen for
my long distance speed riding.
Here is Continental's quick and kind reply:"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.It is obvious that if you give priority to comfort and tracking, you
should prefer af 25 mm to a 23 mm.But even if you give priority to speed, the 25 mm tire appears to be
the better choice. But nobody knows.Here is an uncovered field for an engineer student or for a bicycle
magazine to look in to.Ivar of Denmark
Continental have a star rating for rolling resistance here.
http://www.conti-tyres.co.uk/conticycle/tyre_application/road_application.pdf
Whilst it's only a rough guide it indicates they've made some effort to
investigate the matter.
Marty