Re: Need mental and ratio help! Please!
There should be no difference in your ratio calculation do to the different sprocket types. This would only come into effect if you were trying to use a 6t #25 to a 40t #40. Then you have a problem. But a 40t/6t for a #25 chain is 6.6 to 1 and a 40t/6t for a #40 chain is still 6.6 to 1 so don't let the different sprocket/chain types mess with you.