When to change bottom bracket

[junglegusset]

Hello. I have had bikes for years and in the past I only changed my BB when the axle was sloshing round like a wooden spoon in a jam pan. My current bike (a 1999 Kona Explosif) has still got the original bottom bracket on it, not sure what it is but possibly XT since that's what the rest of the drive train is. There is no play in it and it seems to turn freely, but you can feel a bit of crunching a bit when you are pushing hard on hills etc. I've never had a bb last this long so I am wondering if there is any benefit to be had from replacing it now...or should I wait until it falls to bits as I have with my past bikes? What indicators do people use that they need to replace theirs?

Thanks

Ian

 

[accountantpete]

Give the crank a really good shake from side to side and I think you will find a bit of play in there as the bearings are probably wearing out. All it needs is a new BB compatible with shell and chainset and you are set for another 10 years.

 

[Ian H]

...but you can feel a bit of crunching a bit when you are pushing hard on hills etc...

If the BB is smooth and spins freely with the chain off, then the crunching emanates from somewhere else.

 

[jimboalee]

Hello. I have had bikes for years and in the past I only changed my BB when the axle was sloshing round like a wooden spoon in a jam pan. My current bike (a 1999 Kona Explosif) has still got the original bottom bracket on it, not sure what it is but possibly XT since that's what the rest of the drive train is. There is no play in it and it seems to turn freely, but you can feel a bit of crunching a bit when you are pushing hard on hills etc. I've never had a bb last this long so I am wondering if there is any benefit to be had from replacing it now...or should I wait until it falls to bits as I have with my past bikes? What indicators do people use that they need to replace theirs?

Thanks

Ian

The correct terminology is "like a prick in a top hat".

 

[AlanW]

If the BB is smooth and spins freely with the chain off, then the crunching emanates from somewhere else.

From recent experience that is not always the case, and it seems like the latest type external BB's are more prone to fail than the older style internal one piece ones.

I have repaired a couple of bikes recently and the owners have mentioned odd noises coming from the BB area. I have stripped out the external bearings and they were really smooth and as far as I was concerned ok.

However, in the real world and when under load they were creaking?

This was finally proven, when for the sake of less than £20 for a pair of 105 external bearings, we fitted a new pair and the 'problem' was cured?

 

[Over The Hill]

The correct terminology is "like a prick in a top hat".

or Katie Price

 

[junglegusset]

My head is now swimming with mildly disturbing images following that brief lesson in cycle component analogies!

There is a tiny, tiny bit of play when you try and shake it and it spins freely when the chain is off. I'm starting to think it's not that bad. Just had new pedals and chain, so not sure what's going on. I think I will return to my old diagnostic methods and replace things when they are completely and obviously knackered. Thanks for the input though.

 

[AlanW]

Could even be the freehub making the noises, I've had that before?

 

[mickle]

It's worth removing your BB more frequently than once every decade if only to regrease the threads which can become firmly bonded to the shell through corrosion. And it gives you an opportunity to see whats going on inside the frame; a friend of mine took his BB out recently and a pint of muddy water followed.

Having the BB out of the frame and in your hands is the best way to assess its condition too.

 

[SimonC]

The correct terminology is "like a prick in a top hat".

"like a prick in a shirt sleeve" further north.

 

[Speck]

"like a prick in a shirt sleeve" further north.

Or a sausage in an Alley

 

[Norm]

My preferred simile is "dick in a dustbin".