Shane

I have found 10:1 to approx 10 wheels to be about optimum, in other words - driving wheel dia in inches;1

Mighty Mouse has 6:1 ratio to 5 wheels.

Mod2 gears are good if you are not too precise with shaft positioning, but dont thin down the gears, I have to in Velocirippa and all the gear teeth are bent over.

Trev