We used to use a 10 tooth #35 sprocket on the output of the CIMS going to a 45 tooth "Jack Shaft" (Reduction) which was keyed to two 10 tooth sprockets, which carried chain to the wheel sprockets.
For reference, check out my Whitepaper on our "Standard Drive" here:
http://www.chiefdelphi.com/forums/pa...le&paperid=247
edit::
I realized that these were made in the pre-Inventor days! Ah!
(well, my pre-Inventor days)
so, please bear with them, they were hand-drafted in Anim8or, but should give you an idea of how the system worked.
We used this system (With the CIMS mounted higher) in 2004, and had a really fluid drive system.
Only thing you have to keep an eye on is weight....
__________________
-=Sachiel7=-

There's no such thing as being too simple!
Look for Team #1132, RAPTAR Robotics at the VCU Regional this year!