Bike Cadence & Speed Calculator
Work out your cycling speed from your pedalling cadence (RPM), gearing, and wheel size. The calculator finds your gear ratio, wheel circumference, and how far you travel per pedal stroke, then combines them with your cadence to give speed in km/h and mph. Handy for choosing gears and pacing on the road or trainer.
Formula
Gear Ratio = Chainring / Sprocket. Wheel Circ = π × diameter(m). Speed = Cadence × GR × Circ / 60 m/s.
90 RPM, 50/17 gearing, 700 mm wheel
Inputs
- Cadence: 90 RPM
- Chainring Teeth (front): 50 T
- Sprocket Teeth (rear): 17 T
- Wheel Diameter: 700 mm
Gear ratio = 50/17 ≈ 2.94. Wheel circumference ≈ 2.20 m, so each pedal revolution covers about 6.47 m. At 90 RPM that's roughly 35 km/h (about 22 mph).
Frequently asked questions
How does cadence relate to speed?
Speed = cadence × gear ratio × wheel circumference. For a fixed gear and wheel, pedalling faster (higher RPM) directly increases your speed.
What is a good cycling cadence?
Many riders aim for 80–100 RPM. A higher cadence in an easier gear reduces strain on your knees, while a lower cadence in a harder gear builds force.
How do I change my speed at the same cadence?
Shift gears. A bigger chainring or smaller sprocket raises the gear ratio and speed for the same cadence; the opposite makes pedalling easier but slower.
What wheel size should I enter?
Use your wheel's overall diameter including the tyre — about 700 mm for a typical road wheel, or roughly 660 mm for a 26-inch mountain bike wheel.