Old Britts – Calculate Miles Per Hour for a Commando Gearbox
Download the complete PDF version using the green download button at the top right of this page for detailed Norton Commando gearbox speed and RPM calculation formulas. This technical article explains how to calculate road speed (MPH) from engine RPM or determine engine RPM for a selected road speed using the Norton Commando AMC gearbox ratios and sprocket combinations.
The guide covers gearbox ratios for all four Commando gears and explains how engine sprocket size, clutch sprocket size, gearbox sprocket size, rear wheel sprocket size and rear tire diameter affect final gearing and cruising RPM.
Detailed formulas and worked examples are included showing how sprocket changes affect highway cruising speed, engine RPM and theoretical top speed calculations.
This resource is especially useful for Norton owners tuning gearing for touring, highway riding, racing or performance applications.
Contents Include
- Commando gearbox ratio information
- MPH calculation formulas
- RPM calculation formulas
- Engine sprocket calculations
- Gearbox sprocket calculations
- Rear wheel sprocket calculations
- Rear wheel diameter calculations
- Fourth gear speed calculations
- 1st through 4th gear speed comparisons
- Cruising RPM calculations
- Top speed gearing examples
- Performance gearing guidance
Supported Norton Models
- Norton Commando 750
- Norton Commando 850
- Norton Roadster
- Norton Interstate
- Norton Fastback
- Norton Hi-Rider
- Norton MK3
