Bicycle Mechanics - BB question

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BRANDUNE
11-12-07, 04:27 PM
Hey guys,
I recently built up my first aluminum frame, and I was feeling what I thought was flex in the BB. I could look down and see it moving, everyone just told me it was just frame flex. I took it all apart and regreased and retorqued everything just for my own sanity, now a couple days later I was looking closely and I can see the cups moving in the shell, I'm scared to take it apart, but I am assuming I have stripped my BB shell. My questions are A: how the hell did this happen? and B: is there any solution to this or is my frame now trash?

carpediemracing
11-12-07, 04:39 PM
what kind of frame? do the BB cups press in or do they thread in?

cdr
BRANDUNE
11-12-07, 04:51 PM
Oh sorry, they are threaded, and the frame is generic, I believe it is what they rebrand as the DBR podium

tradtimbo
11-15-07, 10:34 AM
Aluminum is soft, and the threads easily deformed. Is there a chance you cross-threaded the BB on your initial installation, removed, and installed straight? did you properly adjust the bottom bracket before installing your cranks? Its not unheard of for a BB that is not adjusted properly to bind up. any evidence of that? Do you have the same thread types in the shell as on the cups? Is it possible that you used TOO much torque installing the BB? Aluminum threads can be stripped.

I suggest you remove everything and check it all out. Your answer lies inside.
tellyho
11-16-07, 07:51 AM
I've had BB flex in my Cannondale frame. Had to teflon tape the BB threads to compensate. Did you get the BB shell faced before install? This might solve it for you.