Wheel speed in RPM only becomes road speed once you know how far the tyre travels per turn — its circumference. This tool multiplies RPM by tyre circumference and converts the result to miles per hour.
For the ride
Wheel and speed gear.
Bike computer
Track cadence and speed.
Tyre pressure gauge
Keep tyres dialled in.
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Frequently asked questions
What is the RPM to mph formula?
mph = RPM × tyre diameter (in) × π × 60 ÷ 63,360.
Why does tyre size matter?
A bigger tyre covers more distance per revolution, so the same RPM gives a higher road speed.