# Cycling Cadence to Speed Calculator

> Turn pedalling cadence, chainring, cog and wheel size into road speed in km/h and mph, with gear ratio, metres of development and gear inches.

Category: Everyday tools · Applies to: Worldwide · Last updated: 2026-10-29
Interactive calculator: https://calculators.geekmidst.com/calculators/cycling-cadence-to-speed-calculator

Each turn of the cranks moves the bike the gear ratio times the wheel’s circumference. Multiply that by your cadence and you have your speed.

Also called: Bike gear calculator, Gear development calculator.

## Inputs
- Cadence (unit rpm; default 90)
- Chainring teeth (default 50)
- Rear cog teeth (default 15)
- Wheel circumference (unit mm; default 2105)

## Results
- Speed
- Speed
- Gear ratio
- Distance per crank turn
- Gear inches

## Formula

```
Development (m) = Chainring ÷ Cog × Circumference (mm) ÷ 1000;  Speed (km/h) = Development × Cadence × 60 ÷ 1000;  Gear inches = Ratio × Circumference ÷ π ÷ 25.4
```

Where:
- Chainring, Cog: teeth on the front and rear sprockets in use
- Circumference: distance the wheel rolls in one turn
- Cadence: crank revolutions per minute

## Worked example
1. Gear ratio = 50 ÷ 15 = 3.333.
2. Development = 3.333 × 2.105 m = 7.017 m per crank turn.
3. Speed = 7.017 × 90 × 60 ÷ 1000 = 37.89 km/h.

**Result:** At 90 rpm in a 50×15 gear on a 2105 mm wheel you are riding at about 37.9 km/h (23.5 mph).

## What the result means

Use the table to pick gears: if your comfortable cadence is 85–95 rpm, choose the gear that puts your target speed in that range.

## Assumptions and limits
- No wheel slip and the chain is in the stated gear.
- Tyre pressure and load change the rolling circumference slightly.

## Questions

### What is a good cadence?

Most trained road cyclists settle between about 80 and 100 rpm on the flat; there is no single best value.

### What are gear inches?

An old measure: the diameter of an equivalent penny-farthing wheel. Multiply by π for the distance travelled per crank turn in inches.

## Related calculators
- [Cycling Power to Weight Calculator](https://calculators.geekmidst.com/calculators/cycling-power-to-weight-calculator)
- [Speed Calculator](https://calculators.geekmidst.com/calculators/speed-calculator)
- [Ratio Calculator](https://calculators.geekmidst.com/calculators/ratio-calculator)

Source: GM¹X CalcVerse — https://calculators.geekmidst.com/calculators/cycling-cadence-to-speed-calculator