I'm tidying up a bike for a relative with parts box upgrades and was swapping over the cranks to some old deore square taper ones I have. Figured I'd swap the BB too, pretty sure its a 68mm shell and i have a 68mm bottom bracket. When i go to tighten everything up I can't get both sides in flush; one side or the other is always sitting ~2mm proud (depending on which side i put in first). I tried putting the old BB back in and the same thing happend. I've cleaned all the threads up and it all seems fine! It almost seems I'm missing a spacer but I didnt think this was done on square taper bbs?
What daft thing have I done?
Drive side needs to go in all the way. Non-drive side cup goes in as far as it will. Not unusual to have a few mm showing. Do the cranks clear the chainstays equally on both sides?
perfect thanks gecko! I haven't put the cranks on yet cos I wasn't happy with how the bb had gone in, will make sure it's clearing chainstays equally.
It's not an e-type bottom bracket is it? The one that had the front derailleur mounted at BB.
nope definitely not e-type
as geko says.
As geko says.
I had the odd one last week of the non drive side snugging right up to frame - putting a ruler on the BB I think the paint is just very thick...
All that matters is that the cranks don't hit the chainstay.
I bought a Diamondback for Mrs BigJohn many years ago which had a 73mm BB in a 68mm frame. It was fine.
Just use a 2.5mm hollowtech 2 spacer to correct the chainline on a 73mm shell sq taper BB in a 68mm shell.