Tyre width
Jan. 20th, 2016 12:03 am![[personal profile]](https://www.dreamwidth.org/img/silk/identity/user.png)
The tyres on my bike seem to be 35c and 38c width, if I read them right. Would a thinner tyre be better for cycling round Cambridge? I mostly go short distances 1 mile to 4 mile, but it would be nice if there wasn't unnecessary effort, and nice if it was possible to cycle to Shelford occasionally, which right now is possible but a bit too much of a trek to ever want to do it. Or should I be looking at a better bike instead?
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Date: 2016-01-20 08:52 am (UTC)no subject
Date: 2016-01-24 05:43 pm (UTC)Not particularly. The main factor informing rolling resistance is pressure - the higher the better. At a given pressure, a fat tyre has slightly lower rolling resistance. Unfortunately, the main factor informing rider comfort is also pressure - within reason, the lower the better. Hence a fat tyre means you have to compromise less. The risk of pinch flats is also much less on fat tyres, which is more of an issue with a more massive rider.
The reason everyone doesn't use fat tyres is threefold; as Emperor says, sometimes you just can't get to a desired pressure in a fat tyre (but this is not a given - the tandem uses 32mm tyres at 100psi). A fat tyre has higher air resistance but because power to overcome air resistance varies with the cube of speed this is not a significant effect unless you ride very quickly (like, one-testicled American speeds). A fat tyre (and a wide rim to mount it on) are heavier, which may be significant if you are gram-shaving (which we aren't) or believe exaggerated myths about rotating mass (which you shouldn't).
Another highly significant factor is tread. For road riding, tyres should be slick - a bicycle tyre cannot aquaplane at bicycle speeds. Tread pattern causes extra rolling resistance, and fat tyres are much more likely to have significant tread patterns - in particular, off-road knobblies are dog slow on asphalt.
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Date: 2016-01-30 02:58 pm (UTC)