4th bottom bracket

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Antan1
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Joined: 29 Mar 2013, 8:59pm
Location: Bray Co Wicklow Ireland

Re: 4th bottom bracket

Postby Antan1 » 19 Mar 2014, 1:51pm

Rode to the LBS, typical the noise had subsided somewhat, however I have left it with him to check out but I am 99.9% sure it is the BB, I have changed the pedals, checked all bolts etc, chain and cassette are fairly new.
The ones previously fitted were not Shimano BBs all they have written on them is BSA? he reckons they are ok?
Rob
Cannondale SL4 MTB. Trek Checkpoint ALR5

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cycleruk
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Location: Lancashire

Re: 4th bottom bracket

Postby cycleruk » 19 Mar 2014, 2:12pm

Antan1 wrote:Rode to the LBS, typical the noise had subsided somewhat, however I have left it with him to check out but I am 99.9% sure it is the BB, I have changed the pedals, checked all bolts etc, chain and cassette are fairly new.
The ones previously fitted were not Shimano BBs all they have written on them is BSA? he reckons they are ok?
Rob


BSA ? Obviously not O.K. :(

I don't know how much he charges but a Shimano BB-UN55 is only £12.50 :-
http://www.chainreactioncycles.com/shim ... -prod71369

If you have the facilities to install yourself I would buy the tool and DIY it.
There's no such thing as a tailwind.
It's either a headwind, or you're going well.

Antan1
Posts: 79
Joined: 29 Mar 2013, 8:59pm
Location: Bray Co Wicklow Ireland

Re: 4th bottom bracket

Postby Antan1 » 19 Mar 2014, 2:20pm

He charges 16€ fitted for the BBs, I have the tools to replace myself but never bothered as I thought the price was ok for what I thought was a Shimano unit.
You live and learn I suppose.
Rob
Cannondale SL4 MTB. Trek Checkpoint ALR5

Brucey
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Joined: 4 Jan 2012, 6:25pm

Re: 4th bottom bracket

Postby Brucey » 19 Mar 2014, 7:57pm

if they have BSC written on them then this is just the thread standard.

One reason the SHimano BB-UNxx series BB units are reliable is that the centre unit is not greatly disturbed by variations in the BB shell tolerances.

If you have a cheaper 'sealed BB' then it may well have a fitting that locates each bearing separately in a cup, and there is a centre sleeve between them. Many such units are very low quality , have stuff-all grease in them, are badly toleranced, and are quite rough when installed if the BB shell has slightly cocked threads. When they are like that they tend not to last very long.

cheers
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~~~~~~~~~~~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~

tim_f
Posts: 248
Joined: 12 Oct 2009, 10:37pm

Re: 4th bottom bracket

Postby tim_f » 19 Mar 2014, 8:38pm

Best way to check bottom bracket for wear is to take chain off rings and then spin cranks and listen or feel for vibration.

I guess you can eliminate peddles as source of vibration by unscrewing them.

Check that the chain ring bolts are not lose.

rgc_911
Posts: 130
Joined: 7 Feb 2008, 9:34am

Re: 4th bottom bracket

Postby rgc_911 » 21 Mar 2014, 9:37pm

andrewjoseph wrote:shimano square taper bb only lasted 500-1000 km on both my wife's and my early mtb's. went through a few before going to outboard crank/bb set.

we do ride in all conditions and through deep mud and puddles though.

the outboard bb now last 1500-2000km .

square taper on our road bikes last for much longer. as do chain, chain rings, cassettes etc.


I am surprised by that - I have had a square taper BB on my Decathlon MTB for 5 years and it's still fine.

The external BBs (Shimano) on my Cyclocross bike barely last 2 seasons.

I put this down to the grit etc and the lack of proper seals on the external shells.
cheers
Cookie

www.fordcc.org.uk

andrewjoseph
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Joined: 17 Nov 2009, 10:48am
Location: near Afan

Re: 4th bottom bracket

Postby andrewjoseph » 22 Mar 2014, 8:56am

Yes, several people on here expressed surprise at this when I mentioned it previously. That is my experience with 3 different bikes and several shimano un5? BB.

We regularly ride through rivers, very deep muddy puddles, in heavy rain all day.

External BB last us much longer on the mtb.
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trek800
Posts: 3
Joined: 2 Dec 2019, 2:21pm

Re: 4th bottom bracket

Postby trek800 » 2 Dec 2019, 2:30pm

very deep mud puddles, heavy rain and rivers is what is causing them to fail prematurely.
when you get water in the tiny frame hole * above rear tire , bottom frame near dropouts etc
( and water even can go down seat tube)
it settles moisture, even dirt in BB shell as this allows rust to form in BB cartridge.
theres your answer mate!

trek800
Posts: 3
Joined: 2 Dec 2019, 2:21pm

Re: 4th bottom bracket

Postby trek800 » 2 Dec 2019, 2:33pm

also forgot to mention some people coat the BB cartridge with silicone over the sealed areas to make it even more waterproof to stop moisture
in very wet environments .
also keep condensation out of it-- It works !

trek800
Posts: 3
Joined: 2 Dec 2019, 2:21pm

Re: 4th bottom bracket

Postby trek800 » 2 Dec 2019, 2:39pm

a major cause for failure is cranking on one side(like standingup cranking them Up a Hill kills them over time) as this creates a angled force ), and standing on the Bottom bracket often This stress/weakens them.
Seen it many times Not putting all your weight on them makes them last much longer .
cheers Mate!

Marcus Aurelius
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Joined: 1 Feb 2018, 10:20am

Re: 4th bottom bracket

Postby Marcus Aurelius » 2 Dec 2019, 2:51pm

I use splined sealed cartridge BBs on my 29er. They really do need a hell of a lot more torque ( relative to any road bikes I’ve used them on )to get them to feel 100 percent solid. The noises ( clicks and knocks normally ) when they’ve been new, have been sorted by putting loads of grease on the threads in the frame, and loads more on the splines.

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Sweep
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Location: London

Re: 4th bottom bracket

Postby Sweep » 3 Dec 2019, 11:21am

Vorpal wrote:I have never replaced a bottom bracket. Never. In a lifetime of cycling, and many thousands of miles on my oldest bicycle.

I did clean and re-grease one on a late 60s Dawes last year. :)

I'd be concerned that they are not being installed correctly.

Amazing record.
Can we ask what types these are.
I have replaced them - only one I resented having to do was a piece of ISIS junk fitted as original to an exoensive dahon sports folder.
Sweep

Vorpal
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Re: 4th bottom bracket

Postby Vorpal » 3 Dec 2019, 1:36pm

Sweep wrote:
Vorpal wrote:I have never replaced a bottom bracket. Never. In a lifetime of cycling, and many thousands of miles on my oldest bicycle.

I did clean and re-grease one on a late 60s Dawes last year. :)

I'd be concerned that they are not being installed correctly.

Amazing record.
Can we ask what types these are.
I have replaced them - only one I resented having to do was a piece of ISIS junk fitted as original to an exoensive dahon sports folder.

I think most of the them are UN type Shimano BBs. I'm a pretty laid back pedaller. I spin and hardly ever stand on the pedals.
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Steve
Posts: 215
Joined: 2 Apr 2007, 1:42pm

Re: 4th bottom bracket

Postby Steve » 3 Dec 2019, 7:06pm

Antan1 wrote:1st two had side to side movement of the crank arms, this one is making a knocking noise under pressure.
All have been Shimano makes, I don't know the model numbers, fitted by my LBS, no pressure washer used and not over washed around the bottom bracket and wheel seals.
The third one he replaced for free as the second only lasted 300km, I cannot figure it out.
Rob


In my experience, knocking noises under pressure need not mean the thing is knackered, often such sounds come and go, perhaps with variations in weather. If no grinding or play can be felt, I just live with it.

Brucey
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Re: 4th bottom bracket

Postby Brucey » 4 Dec 2019, 12:23am

we really need to know what type of ST BB is being fitted here; there are plenty which are 'compatible with shimano' and even use the shimano splined tool but they vary plenty in how good they are and also (crucially) how sensitive the assembly is to the state of the BB threads and how tightly the thing is installed. On the latter point the most common type of cheap 'cartridge BB' can easily be installed with too much preload on the bearings and this may cause them to fail in a very short period of time.

BTW if your BB makes clunking noises it may not be knackered yet but there is something moving in a way it which it shouldn't and trouble may no be far away. The last thing I would do is ignore any such noises; it might be something which will cause the threading in the frameset to be damaged.

cheers
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