Motorcycle Performance Guide

Calculate Gear Ratios

This program calculates the gear ratios of a motorcycle. The primary drive ratio and overall ratios for each gear are all calculated. Just enter the data in the white boxes below, then click the "Calculate" Button. Pressing the "Reset" button loads the default values into the form.

Engine Sprocket
Clutch Sprocket
Transmission Sprocket
Rear Wheel Sprocket


Primary Drive Ratio ( Engine to Transmission ) is calculated
Final Drive Ratio ( Transmission to Rear wheel ) is calculated
Overall Drive Ratio is calculated

Enter the Transmission ratio   Computed Overall Ratio  
1st gear  
2nd gear  
3rd gear  
4th gear  
5th gear Use a value of 1 if the bike does not have the gear
6th gear  

The reset values displayed are from a 1994 FXDL Harley-Davidson Dyna Low Rider. All late model Harley Big Twin models have similar. The Rear Wheel Sprocket can vary, with belt drive models using a 61, 65 or 70 tooth sprocket. Below is a table of typical values for late model Harley-Davidson motorcycles.

Make Model Engine Sprocket Clutch Sprocket Trans Sprocket Rear Wheel Sprocket 1st Gear 2nd Gear 3rd Gear 4th Gear 5th Gear
HD FXDL Domestic 24 37 32 70 3.24 2.21 1.60 1.23 1.00
HD FXDL Export 24 37 32 65 3.24 2.21 1.60 1.23 1.00
HD FXDL Australia 24 37 32 61 3.24 2.21 1.60 1.23 1.00
HD EVO 883 Sportster 35 56 27 61 4.30 3.15 2.29 1.88 1.00
HD EVO 1200 Sportster 35 56 29 61 4.30 3.15 2.29 1.88 1.00