| Re: New wheels, new tires (difference between 700x25, 26, & 28?)
In article <40ce72a3@news.ysu.edu>,
Frank Krygowski <frkrygow@mousepotato.com> wrote:
>Roger Zoul wrote:
>
>> I've a heavy rider (240lbs). My current wheels (28 spokes on the rear) have
>> 700x26c tires.
>>
>> I've ordered a new wheelset due to spokes breaking on the rear (36 spokes on
>> the rear). I'm thinking of putting 700x25c or 700x28c tires on this
>> one...will I notice any significant differences?
>
>Personally, I'd go with at least 28. If I had your weight, I'd probably
>look at 32 mm, if it would clear the frame and brakes.
>
>A narrow tire might give very slightly less rolling resistance on
>perfectly smooth roads, but if the road has any significant roughness,
>you'll probably be better off with a wider tire.
That is not how I understand it. If you take two tires which are
constructed the same, inflated to the same pressure and placed under
the same load, the widest tire will be the one with the least rolling
resistance since it is the tire which will deform the least at the
contact patch. Racing tires are narrow for other reasons, like improved
aerodynamics and lower weight, qualities which are thought to be a good
tradeoff for the increased rolling resistance. The fact that wider
tires deform less at similar inflation pressures and loads also makes
them less prone to pinch flats, which means that they can carry the
same loads at lower pressures (making them more comfortable at the
expense of rolling resistance) or, similarly, carry heavier loads at
the same inflation pressure.
Dennis Ferguson
|