[fatboy250]

This would be how I would go about choosing new sprockets

Originally Posted by fatboy250

The only problem is that to truly evaluate the final gear ratios (sprockets) you need to know the final ratios of the output shaft coming from the transmission of each bike...just as Red mentioned. Remember, most of us are without a tachometer. So we can't give a you a standard "6500 rpm/mph" reading.

I think the easiest thing to do is find out what you have when you ride yours and decide if you want to change your ratio once you've ridden it. The math isn't that difficult if you know your stock gear ratio and what speed feels comfortable on the engine [desired rpm]. You can simply create [with a sprocket change] the gear ratio needed to then go the speed that you want to go at that [desired rpm]. Remember this is probably going to be different for a guy that is 160lbs compared to someone who is 265lbs. So you have to figure it out for you and yours.

For instance, if all I wanted to do was change my rear sprocket which is 46. And I know that 55 is the comfortable cruising speed [desired rpm] And I would like to go 65 at the same comfortable cruising [desired rpm]
Then it would be simple algebra 55(46)=65x => (55/65)(46)= x => 38 or 39 tooth sprocket.

Luckily my stock sprockets 14/46 are perfect for the type of riding I do. Like Red said the 55mph cruising speed feels comfortable on the Roketas.

Jason