Cycling Speed Calculator
Enter your cadence in rpm, chainring and cog teeth, and wheel circumference to see how fast you are riding in both km/h and mph.
How to calculate cycling speed
- Enter your pedalling cadence in revolutions per minute.
- Enter the chainring (front) and cog (rear) tooth counts.
- Set your wheel circumference in metres, then read km/h and mph.
Examples
90 rpm in 50x15 on 700x25c
cadence 90, chainring 50T, cog 15T, circumference 2.105 m
ratio 3.33, 37.89 km/h, 23.54 mph
Spinning at 100 rpm
cadence 100, chainring 50T, cog 15T, circumference 2.105 m
about 42.1 km/h
Frequently asked questions
How is bike speed calculated from cadence?
Multiply cadence by the gear ratio to get wheel revolutions per minute, multiply by wheel circumference for metres per minute, then convert to km/h or mph.
What wheel circumference should I use?
Use the rollout of your mounted tire in metres. A 700x25c road tire is close to 2.105 m, which is the default, while wider or smaller tires differ.
What is a good cycling cadence?
Many road riders hold 80 to 100 rpm for efficiency. Lower cadence pushes a bigger gear with more force, while higher cadence spins a smaller gear faster.
Why convert between km/h and mph?
Cyclists in metric regions track km/h while riders in the US and UK often use mph. This tool shows both so you can compare with any computer or training app.
Does this account for wind or drafting?
No. It is a pure drivetrain calculation of theoretical speed from cadence and gearing, ignoring wind, gradient, rolling resistance and aerodynamic drag.
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