I bought and isntalled this bottom bracket;

VGEBY1 68X120mm, Thread info: BSA 34.798mm 1.37*24TPI

However the arms was too long. So instead i bought;

Shimano UN300 68X 110mm, Thread info: BSA 1.37*24

However, it seems like this Shimano bottom bracket does not fit in the thread no matter what I do.. Should it fit? It seems like it

  • What exactly have you done?
    – Armand
    Jul 31, 2021 at 13:18
  • How hard was it to remove the old cups? If heat and hacksaws were needed, there's possible thread damage. Adding some photos might help here.
    – Criggie
    Jul 31, 2021 at 22:42
  • 1
    By arms, I think you mean the bottom bracket's spindle. That's the one whose length was specified by 68x...mm - 68mm is the BB shell width (and 1.37*24TPI is, I believe, redundant information since we know it's a BSA BB - those numbers specify the thread pitch).
    – Weiwen Ng
    Aug 3, 2021 at 13:28

1 Answer 1


The critical information here is the three letters "BSA," which indicates the bottom-bracket standard (British). Both BBs are British, so barring a manufacturing defect, they should fit the same. I'm sure you've greased your threads and confirmed that you're screwing the correct cup into the correct side: the right side is reverse-threaded.

  • Thanks you were right! I gave it some more force and it worked :) I was afraid to destroy the threads but it is all good now
    – nammerkage
    Aug 1, 2021 at 12:16
  • In my experience, with enough force any bottom bracket will fit ;-). Really, though, I went through the same-- researched, bought... and then it doesn't fit? No, I just needed to be a little more stern.
    – Andrew
    Aug 5, 2021 at 20:40

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