Can you help me identify the bottom bracket for the following please.

The frame is a Norco One25 (version 3)

It does not appear to have internal threads.

The diameter is approx 6.3cm and the length is approx 7cm

It is an old dirt jump bike style frame - maybe from 2003.

I found a picture of the frame here, https://webimg.secondhandapp.com/w-i-mgl/5af860e8d31b2f5a14ce2cca


enter image description here

  • Spec says "Sealed 19mm Mid BB", which is a BMX style. Bearings press in.
    – mattnz
    Mar 8, 2021 at 21:07
  • thanks - where did you find the spec ? Mar 8, 2021 at 21:20
  • DuckDuckGo gave me this as the first result searching for the brand and model you provided in the question: norco.com/bike-archives/2018/one25 There's a small parts spec sheet linked there
    – Paul H
    Mar 8, 2021 at 21:52
  • Thanks - I have updated the question, with a picture of the frame, I think its from 2003 Mar 8, 2021 at 22:13
  • I found specs for a 2004 which used a KUE Q Z-2000 bottom bracket and crankset. There are lots of threads looking for these obsolete parts, the links to replacements also seem obsolete, Do you have the crank ? That is an important factor as to what will fit.
    – mikes
    Mar 8, 2021 at 22:33

1 Answer 1


It appears to be American. Corroborate 51mm bore. If so that's what it is. It wants a BMX three piece and matching BB, depending on your crank choice. Mid didn't exist in 03, or at least that was a few years before its mainstream emergence.

  • Thanks, are we saying its one similar to this: ebay.co.uk/itm/… the size looks about the same. Mar 9, 2021 at 8:38
  • @garyconstable No, that is a Mid that someone put "American" in the title for no reason. If this is confusing find the BB comparison page on any of the BMX online sellers, ie Dan's Comp or Albe's. You need to measure the bore and confirm it's 51mm. Also confirm that your 63 is an OD measure of the shell. Shell OD is meaningless re standard/type because the wall thickness is arbitrary and has more to do to with the material choice etc. Mar 9, 2021 at 9:18
  • Yes this correct - 51 inside and 63mm outside Mar 9, 2021 at 11:39
  • @garyconstable Yes, so American. Mar 9, 2021 at 18:04
  • I see, something like this - danscomp.com/… Mar 9, 2021 at 22:01

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