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Thread: Crank length

  1. #1
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    Crank length

    Is there an equation or does anyone have a good rule of thumb with respect to determining a crank length for kids? Thanks

  2. #2
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    Quote Originally Posted by DadfromPA View Post
    Is there an equation or does anyone have a good rule of thumb with respect to determining a crank length for kids? Thanks
    There is some good info and a few different formulas mentioned in link below.

    https://bikedynamics.co.uk/FitGuidecranks.htm

    I've seen some other BMX calculators too which are kid centric as well.

    In general this has worked well for us. Better to error on the shorter side than longer.

    16" Bike - around 100mm crank
    20" bike - around 125mm
    24" bike - 140mm or 135mm

    That being said, plenty of kids get along ok on longer cranks even if it's not ideal.

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