BB movement 1-2mm lateral..

[stoatsngroats]

...is this indicating that I need to replace my BB?

 

[Ivan Ardon]

yes

 

[Radius]

or that it's loose?

 

[jayce]

Try tightning if still loose replace

 

[stoatsngroats]

Tthanks guys - I'll start looking around for some tools!

 

[stoatsngroats]

Tools at the ready - (nearly!)

When trying to rid my BB of possible looseness(!), which side should I tighten...

It seems to have more slack on the LHS, so is it just a case of tightening the left ring slightly, or backing it off, tightening the RHS, and then closeing up the left side....?

This is my first dealings with a BB!

Thanks,

 

[spandex]

Try tightning if still loose replace

+1

To tighten it 1st you need to know how it is fitted.

To fit one 1st you put the non drive side (LH. it is the small "cup") in 3/4 of the way in this helps locate the BB. Then you put in the BB all the way slowly at first to make shore it is straight. Now you tighten the LH side to lock the BB in place. If there is some play try and tighten the LH side a bit more!.

To undo/tighten a BB 1st take off both cranks then if you turn the cups towords the frount of the bike they will undo and to do them up turn towords the back. It can help if you have a large washer and use the crank bolt to hold the tool in place but do not forget to keep the washer loose. Doing this will stop the tool slipping and mashing up your BB.

 

[02GF74]

depends on what BB ou have fitted.

The shimano BB that I use, on the drive (RH - chainset) cup side have a shoulder that limits how far they can be screwed in to the bike frame, the LH would have a lock nut and this is the side that you would adjust.

Noe the RH cup uses a LH threaed, LH is RH (normal) thread.

If the BB is moving then either is is worn - depends on the type asthe sealed BB should never wear that much, the cups have come undone - solution as described above or the threads in the frame a kanckered allowing the cups to come lose.

 

[spandex]

The threads only get kanckered by putting the BB in wrong there is no over way they can.

 

[jimboalee]

There is a "Fixed cup" and an "Adjustable cup". The fixed cup is usually on the chainring side.

The fixed cup is coated with threadlock and spannered in so it wont move any further.
True, there should be a shoulder.

Apply grease with a grease gun and slot the balls in one-by-one with a greasy finger.

The axle goes in and then the adjustable cup, pre-loaded with lots of grease and the balls.
Then the "Lock Ring".

Now the tricky bit. Holding the adjustable cup, tighten the lock ring to fix the cup in place.
It should be noted here that when the Lock Ring is tightened, it pulls the cup outward ( slack ) slightly within the thread hysteresis, so thread the cup in tight to let the lockring pull it to the correct adjustment.

It may take several attempts.

Re-adjust after a few hours riding.

If you are buying a new BB set, buy one with a Spanner fit adjustable cup, not one with the four small holes.

If your bike is not going to be entered in a Concours show, fit a cartridge (fit and forget) bracket.

 

[02GF74]

The threads only get kanckered by putting the BB in wrong there is no over way they can.

dunno about that. I bought a s/h raliegh that had damage BB so the cups wre coming loose - didn't look like cross threaded but my theory was that the BB got flooded and the threads rusted away.

can't remember if I fixed it by epoxy or a suntour(?) BB that had some weird cup arrangment.

 

[spandex]

All frames are built with the BB shells pre threaded and then the better makers then rethread the shell to make shore it is right but the s**t ones do not. If the shell did get flooded at any time with the BB in place the rust will just have say a 5 - 10% spread over the shell. It will not effect the tork or move the BB.

By the sounds of it there is something else going on with the BB / BB shell.