Development (technology)

The development or expiration length is the length of the distance that a bicycle covers with one turn of the cranks .

calculation

To calculate the development, you have to know the rolling circumference of the bike and the gear ratios from chainring to sprocket and any hub or bottom bracket gears that may be present .

Note: in the following, the general definition for gearbox is used for the ratio i . In the case of bicycle derailleurs , the reciprocal of i is often referred to as the translation instead .

The rolling circumference U of a 28 inch diameter wheel is for example

${\displaystyle U=2{,}16\,{\text{m}}}$

The translation i of a chainring with 44 teeth and a pinion with 19 teeth is

${\displaystyle i={\frac {19}{44}}=0{,}432}$

The expansion is then l

${\displaystyle \ell ={\frac {U}{i}}={\frac {2{,}16}{0{,}432}}=5\,{\text{m}}}$

With a cadence of one crank rotation per second, the result is a driving speed v of ${\displaystyle f}$

${\displaystyle v=\ell \cdot {f}=5\,{\text{m}}\cdot {\frac {1}{\text{s}}}=5\,{\frac {\text{m}}{\text{s}}}=18\,{\frac {\text{km}}{\text{h}}}}$

literature

• Fritz Winkler, Siegfried Rauch: Bicycle technology repair, construction, production. 10th edition, BVA Bielefelder Verlagsanstalt GmbH & Co. KG, Bielefeld, 1999, ISBN 3-87073-131-1

See also

• Expiry length limitation

Web links

• Pinion calculator for derailleur gears with calculation of the development
• Development calculator for derailleur gears
• Development calculator for hub gears