This simple gearchart is intended to help you figure your way around Hubjub's component range.
It covers all of our stock chainring and sprocket sizes. The figures are presented in the form of gear inches, which is the measurement that you will most often see quoted in newsgroup discussions.
If you're unfamiliar with the concept, it refers to the size of wheel you would be riding if you were on a penny farthing or high wheeler. Honest!
If you think this is a bit archaic, check out Sheldon Brown.
Figuring gears is not an exact science. This is so because the diameter of your rear wheel is affected by your tyre, an inherently variable component. For what it's worth, we reckoned that a 700c road wheel is 27" in diameter, a 29inch offroad wheel is 28" (measure one if you don't believe us) and a 26" MTB wheel really is 26"--which it is, if you ride two point something tyres inflated fairly hard.
If you want to do your own calculations, divide the number of teeth on your chainwheel by the number on your sprocket, and multiply it by the actual diameter of your wheel. If you habitually run low pressures, you might want to knock a bit off that diameter to compensate.