Originally Posted by
rack
smc 5200 40c 7.4v
I am using a 33T pinion for a longer asphalt track with 2.2" rears. Sounds like you would be a similar pinion with 2.1" rears on a medium asphalt track (maybe 32T on med carpet).
Did you do anything with the timing of the Hacker 17.5? Mine remains untouched at their stock setting.