Anyone know the rolling circumference of these tyres - would save me some time tonight setting my computer.
Depends on how much pressure is in your tyres.
just get a big tape measure ? or string then measure it - thats what I'd do 🙂
Best method: Arrange bike so tyre valve is at bottom. Place marker on floor. Sit on bike. Waddle/pedal forwards until one wheel revolution completed. Mark where tyre valve is on floor. Measure between two points.
Or you could measure the diameter of the wheel with the inflated type on it and do:
Pi x diameter to find the circumference.
Pi = 3.14
[url= http://math.about.com/library/blcirclecalculator.htm ]Or just whack the diameter or radius into this[/url]
But the rolling diameter of a vertically loaded tyre is not the same as an unloaded tyre...
😛
It'll make such a minute difference that it doesn't really matter?
2068 is what I tend to use for 26x2.1 tyres, which IIRC is what Cateye used to recommend.
If it's infact 2075mm that's 0.3% difference, so when you think your ride was 25 miles, it was actually 25.075 miles!
poppa - Member
But the rolling diameter of a vertically loaded tyre is not the same as an unloaded tyre...
But there has to be some (likely insignificant) slippage Shirley?
If you are happy with an 0.3% error in your distance reading then fine, but some of us hold ourselves to higher standards. 😆
Just concentrate on riding faster. If you think you're going slower than you really are it should spur you on! Think of it as a training aid.
2075mm at 36psi for me