Development Per Pedal Stroke Calculator

How it is calculated

Development is the distance the bike rolls for one full turn of the cranks: development (m) = (chainring teeth ÷ cog teeth) × wheel circumference (mm) ÷ 1000. The bracket is the gear ratio. Chainring and cog must be whole numbers above zero; a fractional tooth count such as 50.5 shows no result. The circumference goes in millimetres, not metres. If you leave it empty or set it to 0 or below, the tool uses 2100 mm, roughly a 700c road wheel, so that result is an estimate rather than a measurement of your own tyre (50/16 then gives 6.56 m instead of 6.55 m). Ratio and development are both rounded to two decimals.

Common mistakes

• Typing the wheel circumference in metres (2.1) instead of millimetres (2100). The tool accepts it and reports about 0.01 m, so check the unit.
• Entering chainring and cog the wrong way round. The ratio is front teeth divided by rear teeth; swapping 50 and 16 gives 0.32 and 0.67 m instead of 3.13 and 6.55 m.
• Using the wheel diameter or the rim size instead of the rolled-out circumference. The circumference is roughly the diameter times 3.14 and depends on tyre width and pressure, so measuring it beats relying on the 2100 mm default.
• Reading the result as speed. It is metres per pedal revolution only; multiply by cadence to get distance per minute.
• Entering a decimal tooth count. Real sprockets have whole numbers of teeth, and a fraction gives no result.