💨 Bike Speed Calculator
Find your speed two ways — from cadence, gearing and wheel size, or from the distance and time of a ride. Both give you km/h and mph.
The cadence mode is a theoretical figure before wind and rolling resistance.
🧮 Calculate Your Speed
💨 Your speed
Two ways to know how fast you're going
Sometimes you want to know what speed a gear-and-cadence combination will give you — handy for choosing gearing or setting a turbo-trainer target. Other times you just want your average pace from a ride you've already done. This tool does both.
The cadence mode turns wheel size, gearing and cadence into a theoretical speed; the distance mode divides distance by time for a true average. Read exactly how each is derived in the FAQ below.
❓ Frequently Asked Questions
How is bike speed calculated from cadence and gearing?
Each pedal revolution rolls the bike forward by its 'development' — the wheel circumference multiplied by the gear ratio (chainring teeth ÷ cog teeth). Multiply that distance per revolution by your cadence in rpm to get distance per minute, then scale to an hour: speed (km/h) = wheel circumference (m) × ratio × cadence × 60 ÷ 1000. It's the theoretical speed for holding that cadence steadily in that gear, before wind and rolling resistance.
How do I calculate speed from distance and time?
Average speed is just distance divided by time. Enter how far you rode and how long it took, and the calculator returns kilometres per hour and miles per hour. For example, 40 kilometres in 2 hours is 20 km/h. This mode is perfect for checking your average pace from a completed ride or a segment.
Why does my real speed differ from the cadence estimate?
The cadence mode gives an idealised figure — the speed you'd travel if that cadence and gear were held with no losses. In the real world, air resistance (which grows sharply with speed), rolling resistance, gradient, wind and drivetrain friction all slow you down, while a descent or a tailwind can push you faster than the gear alone suggests. Use it to compare gears and cadences, not as a promise of pace.
Does wheel size affect my speed?
Yes — for a given gear ratio and cadence, a larger wheel rolls further per revolution, so it's faster. That's why the same gearing feels different on a 700c road bike, a 650b gravel bike and a 26-inch mountain bike. Pick the wheel size that matches your bike so the development, and therefore the speed, is accurate.