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## A Hub-Gear Calculator for small wheels

(See here for a non-hubgeared calculator).
**How to use**:

Define wheel size by choosing ERTRO/ISO rim diameter **(A)** and tyre width **(B)**. The nominal widths are 25, 28, 32, 35, 37 and 40, etc, but you can input whatever value you like. The calculator 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 variables are the chainwheel size **(C)**, and sprocket size **(D)**.

Finally, select the ratios that correspond to the gear-hub model to be analyzed **(E)**. (See here for a table of gear-hub data).The computation formula used is (A+2B)*25.4*C/D*E/100. The result (yellow fields) is presented in the established "gear-inch" format. Best viewed with the IE font size set to "smallest".