🚴 Cycling Speed from Cadence Calculator

Enter your pedaling cadence, gear ratio, and wheel circumference to calculate your resulting cycling speed.

From pedal strokes to kilometres an hour

The chain gives a fixed relationship between crank and wheel, so speed is pure geometry - no power, weight or gradient enters into it:

wheel rpm = cadence × (chainring / cog)
speed km/h = wheel rpm × circumference(m) × 60 / 1000

At 90 rpm in 50x14 the ratio is 3.57, so the wheel turns 321 times a minute. On a 2105 mm wheel that is 676 m every minute, 40.6 km/h, or 25.2 mph. Halve the cadence and you halve the speed; shift from the 14T to a 21T sprocket and the ratio drops by a third, taking the speed with it.

Getting the circumference right

TyreCircumference
700 x 23c2096 mm
700 x 25c2105 mm
700 x 28c2136 mm
26 x 2.02074 mm
29 x 2.22326 mm

For your own wheel, do a roll-out: sit on the bike, line the valve up with a mark on the floor, roll forward exactly one revolution and measure between the marks. Rider weight squashes the tyre, which is why a loaded roll-out comes out 10-15 mm shorter than the chart.

This is the speed the drivetrain produces while you are actually turning the pedals. Average speed over a ride is always lower, because it includes coasting, corners and stops. Tyre pressure, load and wear all move the rolling circumference by a few millimetres, which is a fraction of a percent - fine for gear choice, worth redoing if you are calibrating a bike computer.

Frequently asked questions

How fast is 90 rpm in a 50x14 gear?

40.6 km/h, or 25.2 mph, on a standard 700x25c wheel. That is a fast group ride pace, which is why 50x14 is a flat-road gear rather than a climbing one.

What is a good cadence for cycling?

Most riders settle between 80 and 100 rpm on the flat. Lower cadences load the muscles harder, higher ones shift the cost to your heart and lungs, and trained riders tend to drift upward over time.

How do I measure wheel circumference for a bike computer?

Roll out one full wheel revolution with your weight on the bike and measure the distance in millimetres. It beats the chart because it captures your tyre, your pressure and your weight.