Ha ha, if you really wanted to make it as general and nerdy as possible you could make it possible to have gears as small as a single tooth, which would spin once every time a link went past it.. Perhaps you could even venture into the uncharted realms of negative teeth (which you'd arguably get if you looped the chain as a figure 8), or no teeth (would that spin at an infinite rate?).

This is cool as is though, thanks for putting it together! It seems to run a bit quicker than other gear calcs I've tried.