bottom bracket serviceable?

[MattDB]

Hi, my bottom bracket is creaking. Last bike I had it was a sealed unit, I took out out and put in the same type. My new (30 year old) bike has a creaking bb but I think it's the type with ball bearings in. Just wondering what dictates whether this can be serviced or needs replacing?

Matt

 

[mrandmrspoves]

The answer is the amount of wear and tear that you find when you open it up.
Ball bearings can be replaced cheaply enough - but if the cups or the axle are worn too, then you may as well bin the lot. Even if it is serviceable, the best way forward is probably to take it all out and replace with a Shimano UN55 sealed cartridge - which will cost you about £12.

 

[the_mikey]

Generally the BB cups aren't worth servicing, just replace them. Also are you sure the BB is the cause of the creaking? It can be frustrating to replace all the parts you think are creaking only to find the creak persists after..

 

[smokeysmoo]

Strip it and chuck a UN55 in, problem solved.

 

[sidevalve]

Strip it - clean it - replace the balls -regrease and there is a 99% chance it will be fine. Such bearings were designed to last a LOOONG time. The modern stuff isn't - it is designed to have a finite life so you will buy another. I would check as above that it really is the BB however - pedals can do a really good imitation of a worn BB.

 

[MattDB]

Lovely thanks very much - I was assuming it was the BB as it was when I stand up on the pedals to get up a big hill - if it was the pedals making the noise what would I be looking for in terms of wear?

I'm slowly replacing bits on the bike as it seems like just about everything is original and really worn, so I might put a new BB in anyway - Just looking at the website there are a load of different sizes - is it likely to become clear what size I need once I've removed the old one? Last time it was written on but if it's bearings it might not?

 

[mrandmrspoves]

The length of the crank should be replaced by one the same length. It may be stamped on it or you may have to measure it. Unless your bike is a foreign exotic brand the other measurement (cup width) is likely to be 68mm. If you take the old bits to your LBS they will make sure you get the right replacement and are not likely to cost a lot more than ordering on line.