Quote:
Originally Posted by oldtamiyaphile
Thing is we all 'knew' that higher pressures were 'faster'. That's how it 'feels' and 100% of riders 'know' that. Now dyno and wind tunnel testing have shown those seat of the pants instincts to be mistaken.
In short, if you have particularly rough roads you may have better results in a more compliant, wider tyre running at a sensible pressure, if you drive on polished concrete go narrow and pump it up till they bulge!
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My understanding of this is that "faster" on bicycle tires isn't strictly rolling resistance. Having very hard tires increases rider fatigue, even if the bike rolls easier, so you find people can't put as much power to the road for as long. It's a human limitation which motors do not share.
Correct me if I'm wrong, but a smaller contact patch will result in less rolling resistance, and there are several ways to achieve this. Adding pressure reduces sidewall flex, and sidewall flex eats less forward motion. However, sidewall flex is also what gives a suspension effect, because it also eats vertical motion. The reason we use hollow tires filled with air is not for speed, but for comfort, and to prevent irregularities in the road from tearing our vehicles to bits.
All else being equal, it's better for rolling resistance if the contact patch is longer and less wide, so if you're shooting for lowest rolling resistance possible (often at the expense of ride quality) you'll want very narrow tires with a relatively large diameter - approaching the shape of a bicycle tire.