Bottom Bracket - signs of failure

[Nomadski]

If it's a Campag groupset the movement might be due to the crank not being properly tightened and you might end up 10 miles from home with it coming completly unscrewed and you being left with a pedal and crank attached to your cleat. You might also have to pedal the next three miles one legged whilst waiting for your @Nomadski to go to the bike shop and back for a 10mm allen key. DAMHIKT.

Sounds like a crazy scenario that would never happen.

Although a quick google search turned up this random image...

 

[mjr]

[QUOTE 4862110, member: 9609"]Is there any figure given for max amount of lateral play for a BB. mine is 1.04 180mm (ish) from centre[/QUOTE]
I suspect it's just whatever will still fit the chain through the mech! The movement is probably also adding a little wear to the chain but I doubt it's significant compared to everything else that happens.

 

[andrew_s]

View attachment 326805
Quiz:
Can anyone spot why I thought it worth taking a photo of the old BB after I'd unscrewed it from the frame?

Since nobody got the answer, on the old BB (bottom) you'll see that the LH unflanged collar is attached to the cartridge, but the RH flanged collar is loose, but on the new BB (top) it's the other way round.

Normally the flanged collar is a permanent part of the cartridge (or so I thought), but in this case, I greased the threads, but failed to grease the inside of the loose collar before I fitted it. The collar on the UN72 was aluminium, and by the time the bearings started to fail, the cartridge had been in place long enough that the collar had started to corrode. Aluminium oxide takes up more space than aluminium, so the collar was so tight it was immovable. Eventually, I tried unscrewing the flanged side, and finally got it to move by jumping up and down on the end of a 32 mm ring spanner, exerting what I later guessed to be some 300 - 350 Nm of torque. When the RH flanged collar came out, it didn't bring the cartridge with it as I'd expected, but left it behind still stuck in the LH collar.

P.S. the image is on Photobucket, which is an ad-infested place these days<Clicking on the image will take you there. I recommend that you use the up arrow to go to the original post if you want a full-size image.

 

[andrew_s]

[QUOTE 4862110, member: 9609"]I wonder how long I can keep it going - the new one is still in the drawer.
Is there any figure given for max amount of lateral play for a BB. mine is 1.04 180mm (ish) from centre[/QUOTE]
Not really.
I got irritated by the effect of the play on my pedalling (I was getting a bit of a clunk as it went from one side to the other) before anything like the chain derailing itself happened