RPM = (S × Sr × Pc × G × 88.00) ÷ (Tc × Sf × Pm)
Speed = (RPM × Tc × Sf × Pm) ÷ (Sr × Pc × G × 88.00)
S Speed (miles per hour)
RPM Engine revolutions per minute
Sr Rear sprocket tooth count, secondary drive
Pc Clutch sprocket tooth count, primary drive
G Gear ratio
Tc Circumference of rear tire: (diameter (ft.) X 3.1416)
Typical tire is 25” in diameter
Example: 2.083ft. (25”) X 3.1416 = 6.54ft.
Sf Front pulley/sprocket tooth count
(tranny output, secondary drive)
Pm Motor sprocket tooth count, primary drive