I thought I would share with you all a mistake I made. Hopefully it will prevent anyone from doing the same mistake.
OK, when I bought my frame about 18 month ago, for some reason I picked a BB30 bottom bracket. The short story is:
As my current cranks were Shimano 24 mm axle I should have picked a regular BSA.The long story is that I thought that:
- BB30 is new, I will probably want to upgrade my cranks to 30 mm axle in the future: WRONG (still use my XT cranks and love them!)
- BB30to24 converters exist and they produce a more robust BB, because you have the BB30 shell plus the converter, VERY strong then: VERY WRONG
Let me explain why it is very much wrong.
First, a BB30to24 converter needs to sit on a solid planar surface (the aluminum shell). A BB30 bottom bracket is NOT designed for cups to sit on the shell, but inside. So, when you buy a BB30, the vendor rightfully lacquers the outer side of the BB30 shell. It looks very nice like that. So, my BB30to24 was tighten at 40 Nm on the lacquer, and after 18 month, the lacquer was damaged and my BB was loose.
I understood then that I should nicely cut the lacquer around to expose the shell to the BB30 converter. Smart idea
The next thing that happened is that the shell started to slide away from the frame. Not much 5 mm. Still enough to cause chain line disaster. I know, the design of the BB shell is really poor, there was nothing to prevent the shell from sliding except the lacquer (no pin, screw).
I have finally fixed it. The shell was still very tight in the frame, so I hammered out about 2 cm so that I could clean the surfaces and inject some slow curing epoxy, and hammer the shell in again.
It's now fixed and very solid, but really if I had picked a BSA BB nothing of that would have happen. Stick to it if you can, but don't use BB30to24 if you can't (use BB30 then!!).
