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Noticed that the BB on my daughters 24" wheel Cube had some play in it at the weekend so took it apart, greased it up and refitted. It's the old type with cage bearings.
One ride later the play is back so I assume it could do with replacement, so I've measured up with the intention of getting a sealed unit. BB shell is 73mm and the spindle length is around 127/8mm (I don't have callipers). Quick search online and the only BBs with that spindle size are 68mm shell. Most of the BBs have much shorted spindles (115mm or suchlike). I had a look at the BB on my older daughter's new Orbea which is a square taper too, and that also seems to be a similar size to the Cube.
Am I missing something obvious as I thought it would be a lot easier to find the BB I need and I'd much rather not look for one of those horrible old cotter BBs.
Probably easier taking it out of the frame & the size should be printed on it.
It's not a cartridge unit at the moment so that won't help. I'm guessing it's 127.5mm which seems difficult to find but may have one in decathlon (actually no, thats a 68mm shell too).
Shimano make a 73mm 122mm sealed bb
https://www.freewheel.co.uk/shimano-bb-un55-bottom-bracket-varbbun55
Right, am I being a bit stupid here. Are 68/73 basically the same size BB and a 68mm shell just uses more spacers?
So long since I've worked on 'old' style BBs!!
Are 68/73 basically the same size BB and a 68mm shell just uses more spacers?
No
Go to Sheldon Brown’s web site. All will become clear.....
One ride later the play is back
Tighten it up and see how it goes. This is normal.
Sheldon Brown in clear as mud!!
I'll have another go at the BB over the next couple of days and see if I can adjust it better. I'm more surprised how hard it is to find a replacement in the correct size!
Spa Cycles in Harrogate, or St John Street Cycles are always worth a look for unusual bottom brackets.