Originally Posted by
Jonny5
32/69 seems overgeared to me. Try a 75 pinion also, the larger spur gear, even with the same ratio as a smaller spur, will generate more torque due to it having more leverage.
No, one cannot divorce the spur gear from the pinion, and say the bigger spur generates more torque. The spur gear has to be viewed in relation to the pinion gear used.
By definition, Gear Ratio, Torque Ratio, and Mechanical Advantage are all equal (i.e. the gear ratio is the torque ratio is the mechanical advantage). If two different pinion/spur combinations achieve the same gear ratio, they have the same torque ratio.
There may be reasons to prefer achieving a given gear ratio with larger gears. More teeth being engaged at any given time, the larger gears may run smoother. Or longer gear life because wear is being distributed over more teeth.