Anonymous asked in SportsCycling · 1 month ago

Bottom bracket size?

I have an old bike with a measured bottom bracket width of 116 mm. It needs replacement. I can only find 115 mm and 118 mm width bottom brackets. Which one is a better replacement?


I got two conflicting answers online so far. One says it is okay to be either + or -1mm, but another says I should go for the larger size because it will just space the pedals farther apart. 

3 Answers

  • 3 weeks ago

     it's very important to make sure you get the correct bottom bracket for the job. With so many “standard” sizes available, it may seem overly complicated 

  • David
    Lv 6
    1 month ago

    Well, how did the crank arms sit with the old BB? 

    If there was a decent gap between crank and BB shell, and between cranks and chainstays, then you could PROBABLY use the 115 mm BB.

    If it was a tight fit anywhere with the old BB, go for the longer one.

    Be advised that BB/crank fit can be tricky. Parts that SHOULD fit might not.

    Also, what do YOU like?

    There’s a kinda-sorta advantage to running short ones, but the big thing is you being comfortable on the bike.

  • 1 month ago

    Without knowing what the bike is, how do you expect anybody to answer the question? Take the bike to a reputable bicycle shop. There they can best answer your question. 

    Source(s): Motorized bicycle owner and builder.
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