Originally Posted by
caloso
To simplify, you'd want to have chains with an equal number of links. And to do that, you'd have to have an equal number of teeth. So for every tooth added to the bigger cog, you'd have to subtract a tooth from that side's chainwheel. For example if the drive side is 44x15, the left side would have to be 40x19.
right, chain tension is one factor.
though I think that you could have something like a 39x13 on one side and a 51x17 on the other side -- not that that would make any sense.