Ratio i Calculating

Z1 = Driving gear
Z2 = Driven gear

Driven gear/Driving gear = i

Z2:Z1 = i






Example

i = Z2/Z1 = number of teeth-driven gear/number of teeth-driving gear

iG = Gear ratio = ZG2/ZG1 = 31/37 = 0.838

iA = Final drive ratio = ZA2/ZA1 = 37/10 = 3.700

i tot. = Total ratio = iG x iA = 31/37 x 37/10 = 0.838 x 3.700 = 3.100