{
    "name": "Cycling Cadence to Speed Calculator",
    "url": "https://calculators.geekmidst.com/calculators/cycling-cadence-to-speed-calculator",
    "markdown": "https://calculators.geekmidst.com/calculators/cycling-cadence-to-speed-calculator.md",
    "category": "Everyday tools",
    "description": "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.",
    "summary": "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"
    ],
    "applies_to": "Worldwide",
    "last_updated": "2026-10-29",
    "computation": "Results are computed in the visitor’s browser on the HTML page. This API describes the calculator; it does not compute results.",
    "inputs": [
        {
            "name": "cadence",
            "label": "Cadence",
            "type": "number",
            "default": "90",
            "unit": "rpm"
        },
        {
            "name": "chainring",
            "label": "Chainring teeth",
            "type": "number",
            "default": "50"
        },
        {
            "name": "cog",
            "label": "Rear cog teeth",
            "type": "number",
            "default": "15"
        },
        {
            "name": "wheel_circ",
            "label": "Wheel circumference",
            "type": "number",
            "default": "2105",
            "unit": "mm"
        }
    ],
    "outputs": [
        {
            "key": "speed_kmh",
            "label": "Speed",
            "format": "number"
        },
        {
            "key": "speed_mph",
            "label": "Speed",
            "format": "number"
        },
        {
            "key": "gear_ratio",
            "label": "Gear ratio",
            "format": "number"
        },
        {
            "key": "development",
            "label": "Distance per crank turn",
            "format": "number"
        },
        {
            "key": "gear_inches",
            "label": "Gear inches",
            "format": "number"
        }
    ],
    "formula": {
        "text": "Development (m) = Chainring ÷ Cog × Circumference (mm) ÷ 1000;  Speed (km/h) = Development × Cadence × 60 ÷ 1000;  Gear inches = Ratio × Circumference ÷ π ÷ 25.4",
        "variables": {
            "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": {
        "inputs": {
            "cadence": "90",
            "chainring": "50",
            "cog": "15",
            "wheel_circ": "2105"
        },
        "steps": [
            "Gear ratio = 50 ÷ 15 = 3.333.",
            "Development = 3.333 × 2.105 m = 7.017 m per crank turn.",
            "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)."
    },
    "interpretation": "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": [
        "No wheel slip and the chain is in the stated gear."
    ],
    "limitations": [
        "Tyre pressure and load change the rolling circumference slightly."
    ],
    "rules": null,
    "faqs": [
        {
            "question": "What is a good cadence?",
            "answer": "Most trained road cyclists settle between about 80 and 100 rpm on the flat; there is no single best value."
        },
        {
            "question": "What are gear inches?",
            "answer": "An old measure: the diameter of an equivalent penny-farthing wheel. Multiply by π for the distance travelled per crank turn in inches."
        }
    ],
    "sources": [],
    "related": [
        {
            "name": "Cycling Power to Weight Calculator",
            "url": "https://calculators.geekmidst.com/calculators/cycling-power-to-weight-calculator"
        },
        {
            "name": "Speed Calculator",
            "url": "https://calculators.geekmidst.com/calculators/speed-calculator"
        },
        {
            "name": "Ratio Calculator",
            "url": "https://calculators.geekmidst.com/calculators/ratio-calculator"
        }
    ],
    "disclaimer": null,
    "publisher": "GM¹X CalcVerse"
}