How Motorcycle Speedometers Calculate Speed
Understanding how your motorcycle speedometer calculates speed is crucial for safe and efficient riding. This calculator helps you determine your bike’s speed based on its wheel size, engine RPM, and gear.
- Enter your motorcycle’s wheel size in inches.
- Enter the engine’s RPM (revolutions per minute).
- Select the gear you’re in.
- Click ‘Calculate’ to see your speed and a visual representation.
The formula used to calculate speed is: Speed = (Wheel Circumference * RPM * Gear) / 63360. Here’s how it works:
- Wheel Circumference is calculated as π * Wheel Size.
- RPM is the engine’s revolution per minute.
- Gear is the current gear you’re in.
- The constant 63360 is used to convert the result into miles per hour (mph).
Real-World Examples
Let’s calculate the speed of a motorcycle with a 19-inch wheel in 3rd gear at different RPMs:
- 1000 RPM: Speed = (3.068 * 1000 * 3) / 63360 = 48.2 mph
- 2000 RPM: Speed = (3.068 * 2000 * 3) / 63360 = 96.4 mph
- 3000 RPM: Speed = (3.068 * 3000 * 3) / 63360 = 144.6 mph
Comparison of Wheel Sizes
| Wheel Size (inches) | Circumference (feet) |
|---|---|
| 17 | 5.30 |
| 18 | 5.64 |
| 19 | 5.98 |
| 21 | 6.58 |
Speed vs. RPM at Different Gears
| Gear | RPM | Speed (mph) |
|---|---|---|
| 1 | 1000 | 16.1 |
| 2 | 1000 | 32.2 |
| 3 | 1000 | 48.2 |
| 4 | 1000 | 64.3 |
| 5 | 1000 | 80.4 |
| 6 | 1000 | 96.5 |
Expert Tips
- Always ensure your speedometer is calibrated correctly for accurate readings.
- Consider wind resistance and other external factors that can affect your speed.
- Regularly check and maintain your motorcycle’s tires for optimal performance.
What if my speedometer reads differently?
Your speedometer may have a different calibration or your wheel size might be different. Use this calculator to find your actual speed.
Can I use this calculator for other vehicles?
This calculator is specifically designed for motorcycles. For other vehicles, you may need to adjust the formula or use a different calculator.
For more information on motorcycle speed and safety, visit the NHTSA’s motorcycle safety page and the Motorcycle Safety Foundation.