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## A Gearing Calculator for multi-sprocketed directly-driven small wheels

(See here for a hub-gear calculator).
*How to use*:

Define wheel size by **(A)** choosing ERTRO/ISO rim diameter and **(B)** tyre width. The nominal widths are 25, 28, 32, 35, 37, 40 etc, but you can input whatever value you like. The calculator formula (A+2B)*25.4*C/D_{1}, D_{2}, D_{n} assumes that tyre-width equals the tyre's actual "height", i.e. half the difference between the outer tyre diameter and the rim seat diameter.

The next variable **(C)** is the chainwheel size.

Finally pick a nice set of freewheel sprocket sizes **(D)**.

The result for each "speed" (yellow fields) is presented in the established "gear-inch" format. Best viewed with IE font size set to "smallest".