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Crank Length?


As you all have probably encountered when trying out a new bike is that the crank length may be a bit too long or too short, I'm a total newbie at owning a bike so I don't really have experience in the field, but I was wondering if there are any formulas or guidlines that helps determines what correct Crank length for their bike is, as when I try and cycle with a normal 170mm crank length I find it very unnatural after a while.




  • treefrogtreefrog Posts: 1,242
    The standard lengths for road/tri bike cranks are 170mm, 172.5mm & 177mm. Most riders use 172.5 on road bikes, but some generally bigger riders tend to 177's. Tom Boonen and Miguel Idurain used 177's and set off a trend for the longer cranks - but you must remember your physics the 177's may give more leverage but require more energy to rotate. Conversely 170's are more suited to smaller riders as they take less energy to rotate but the "return" is not as high (if you know what I mean). That is why most mere mortals use 172.5's you get the best compromise between energy in and energy out plus spares are easier to get!
  • treefrogtreefrog Posts: 1,242
    oops for 177 I meant 175!

    Although 177's are available for supermen!
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