Bicycle Mechanics - why is it...

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uhm...yea.
04-19-02, 07:16 AM
... that I can't seem to get a bottom bracket tight without the non-drive side cup cracking? I cracked a second one tonight. :mad: I'm buying 68mm BB's, and i measured my BB shell with a micrometer, but the NDS cup has cracked both times with at least 1.5mm left before it was flush. so, any suggestions?

mike
04-19-02, 07:19 AM
Whoa, man, you are doing something "not-right".

Why are you tightening so tight? I would think you would feel it before you cracked a cup.

Are you sure ALL the bearings are the same size?
bikerider
04-19-02, 07:37 AM
Originally posted by uhm...yea.
... that I can't seem to get a bottom bracket tight without the non-drive side cup cracking? I cracked a second one tonight. :mad: I'm buying 68mm BB's, and i measured my BB shell with a micrometer, but the NDS cup has cracked both times with at least 1.5mm left before it was flush. so, any suggestions?

Yes, don't worry about getting it perfectly flush.

John E
04-19-02, 07:58 AM
Since cup thicknesses and spindle bearing widths vary, most BB systems use at least one adjustable cup. (Some enterprising souls put adjustable cups on both sides of Italian or French BBs, for chainline fine-tuning.) It is perfectly acceptable for the outer edge of the adjustable cup not to be flush with that of the lockring.

This raises the question of whether anyone has read a torque spec. for a cartridge-style BB. With a conventional loose-bearing BB, this was never an issue, because the bearings and spindle would seize up long before either cup would crack.
uhm...yea.
04-19-02, 07:02 PM
ah, so it doesn't need to be flush? i thought it was supposed to be flush, that would then be my difficulty. :rolleyes:
VegasCyclist
04-19-02, 07:20 PM
yep, the cup on mine is out about 2mm or so, I just tightened it to the point where it was about as tight as I could get it, without beating on it with a hammer or something hehe :crash:

hope this helps :D
bikerider
04-19-02, 07:46 PM
By the way, a local shop should have some non-drive-side cups around - you shouldn't have to buy an entire new bottom bracket. I assume these were plastic cups?
uhm...yea.
04-20-02, 08:49 PM
one alluminum, one plastic. the LBS is almost out of BB's, much less cups.