Bike Cadence and Speed Calculator
Find speed from cadence and gearing.
Find how fast you'll go at a given pedaling cadence and gear.
How the Math Works
The Bike Cadence and Speed Calculator uses a straightforward mathematical relationship between your pedaling rate and the mechanical advantage of your bike's gearing system. The formula speed = cadence × (chainring/cog) × circumference × 60 ÷ 1000 converts revolutions per minute (RPM) into kilometers per hour. The chainring-to-cog ratio determines how many wheel rotations occur per pedal stroke, while the wheel circumference (typically 2.1–2.3 meters for standard road bikes) converts rotations into linear distance. Multiplying by 60 converts minutes to hours, and dividing by 1000 converts meters to kilometers.
Practical Applications
To use this calculator in practice, first determine your current cadence by counting how many times you pedal in one minute (many cycling computers and smart trainers display this automatically). Next, identify your chainring teeth count (the front sprocket, typically 42–53 teeth on road bikes) and cog teeth count (the rear sprocket, typically 11–32 teeth). Measure your wheel circumference or use a standard value (2.135 meters for a 700x23c tire). Input these values into the formula or calculator to instantly see your speed in km/h, helping you optimize gear selection for different terrain and riding conditions.
Day-to-Day Use
This calculation is invaluable for cyclists of all levels who want to train more effectively or understand their performance metrics. By knowing your speed at specific cadence and gear combinations, you can establish target paces for interval training, compare effort levels across different routes, or simply verify whether you're maintaining an appropriate cadence for efficient pedaling. It also helps when shopping for a new bike or gear, as you can predict how different chainring and cog combinations will affect your speed on climbs versus flats, ultimately making your cycling more efficient and enjoyable.
Worked example
90 RPM, 50/14, 2.1 m → ~40.5 km/h.
FAQ
Ideal cadence?
Many cyclists target 80–100 RPM.