Originally Posted by
daleburr
You'll certainly need something smaller than the kit spur. This gear chart here shows what will mesh:
http://abram.eu.org/gear_tc6.php
I'd start with your 21.5 gearing and increase the FDR by 0.5 to 1.0.
I think this chart is really nice, but it is not entirely accurate...I have been running 31/104 64p and according to this chart that wont fit.