Bicycle Mechanics - Bottom bracket unthreads

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daveed
05-12-05, 06:59 PM
Hello,
Today I noticed the BB fitting (the plastic shell) on the right crank of my fixed gear bike had unthreaded about a third of the way, in the process leaking grease over the crank, chainring and chainstay (my leg, too). If it matters, the BB is relatively new Shimano ($22); I run a decent chainline and chain tension (not too tight). To get that line, however, the crank is nearly flush against the shell.

Does the unthreading suggest that I didn't tighten the BB down enough on the crank side side? Or does the unthreading portend larger problems?

Also: should I simply tighten the BB back into the shell or should I pull the BB out, look for damage, clean it and regrease?

Thanks.

Dave

operator
05-12-05, 08:25 PM
BB is english threaded?
matt swindell
05-12-05, 09:00 PM
BB is english threaded?
I am almost 100% sure his BB is english. Dave- is this on your older bike(matte black) or your new one, just wondering?

sydney
05-12-05, 09:02 PM
I am almost 100% sure his BB is english. Dave- is this on your older bike(matte black) or your new one, just wondering?English thread drive side tightens counterclockwise,and should not be self loosening.I don't understand plastic shell on the drive side unless using one of the cheapo shimano BB that installs from the left side and what came loose is the plastic 'lockkring'?
daveed
05-13-05, 06:14 AM
Sydney & Matt,

Thanks for the replies. Mistake on my part: It's the BB's metal lockring on the right side, tightens counter-clockwise. It unthreaded a bit, as I said (from back-pedal braking?).

Cheapo? I paid $22 for the Shimano U73 (?). There is a plastic lockring ont he left side. That's nice and tight. Hope that clears things up.

Oh, yes, English threaded.
sydney
05-13-05, 06:42 AM
Sydney & Matt,

Thanks for the replies. Mistake on my part: It's the BB's metal lockring on the right side, tightens counter-clockwise. It unthreaded a bit, as I said (from back-pedal braking?).

Cheapo? I paid $22 for the Shimano U73 (?). There is a plastic lockring ont he left side. That's nice and tight. Hope that clears things up.

Oh, yes, English threaded.The reference was to 'el cheapo' shimano BB(there are such things), not a $22 un73. Loosen the left side 'lockting', retighten drive side to proper torque and then retighten 'lockring'. Shouldn't have come loose if properly tightened.