Bottom bracket noise - not creaking.

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SpokeyDokey

68, & my GP says I will officially be old at 70!
Moderator
Been messing about with my bike all week trying to stop a noise from down below. Initially thought it was wheels.

BB is FSA Megaexo AL-86 with FSA Gossamer Pro crankset.

When I pedal hard eg uphill and out of saddle there is what can only be described as a sharp crack sound - as the pedal (either side) hits it's low point. It is not a really load noise but is enough to irritate the living daylights out of me.

So - pedals off and threads greased.

Chainring bolts removed and regreased.

Removed crankset - all very clean. Cleaned everything anyway to be on safe side. Greased obvious bits.

Reinstalled to correct torque (NDS crank bolts x 2 and preload 'nut').

Still does it.

Basically it goes like this.

LH pedal in down position - apply sharp load and crack. Apply sharp load again and no crack!

Wander around to RH pedal and apply sharp load and crack. Apply sharp load again and no crack.

Repeat ad-nauseum.

***

As the BB is push fit I guess it is a dealer job.

Is it likely to be new bearings required? Or just get the things out and clean where they sit inside the frame?

NB: I have even had the water bottle cage bolts out, FD loosened, seat post loosened, headset & bars loosened in case it was something apparently unrelated to the BB area. All to no avail.
 

steve50

Disenchanted Member
Location
West Yorkshire
Oddly enough I have the exact same issue wih my scott project bike, i have tried the same "cures" as you and still the noise persists, i have a brand new BB on the way as I type.
Your BB is sealed cartridge type , the same as mine so complete replacement required.
 

Lonestar

Veteran
33jpwtj.jpg


Had trouble with mine.After removing it and refitting it,it became loose again after two commutes.Fitted new one and after two more commutes and it seems fine.
 
OP
OP
SpokeyDokey

SpokeyDokey

68, & my GP says I will officially be old at 70!
Moderator
Well...update:

Stripped the whole lot down again - even took the ball bearing race thing out (fiddly bugger to get the bearings back in place) and put it back together and it still did the cracking noise. Aaaaargh!

So then I had the inspired idea of trying to over-torque the piddly little pre-tensioning crank bolt by 0.5Nm and...

...noise gone.

I realise that the BB may well explode when I ride it but it's a price worth paying for silencio!
 
Last edited:

MALT

Active Member
When I had this it was cured by tightening the crank BB bolts. Not saying yours are loose though. Check that the taper is actually being tightened to - if the bolt is bottoming out in the threads, or if the female taper is slightly too large, you may get the same thing.

Just tracked down a creaking that I was sure was in the BB to the rear wheel bearing. Lubed it and problem solved.

Good luck!
 

MichaelO

Guru
Well...update:

Stripped the whole lot down again - even took the ball bearing race thing out (fiddly bugger to get the bearings back in place) and put it back together and it still did the cracking noise. Aaaaargh!

So then I had the inspired idea of trying to over-torqued the piddly little pre-tensioning crank bolt by 0.5Nm and...

...noise gone.

I realise that the BB may well explode when I ride it but it's a price worth paying for silencio!
I am having this exact same problem, and it's doing my head in. Noob question - what's the "pre-tensioning crank bolt"?
 
OP
OP
SpokeyDokey

SpokeyDokey

68, & my GP says I will officially be old at 70!
Moderator
I am having this exact same problem, and it's doing my head in. Noob question - what's the "pre-tensioning crank bolt"?

@MichaelO

It's the big bolt/nut thingy in the centre of the non-drive side crank. Like this:

http://www.winstanleysbikes.co.uk/product/32759/FSA_Mega_Exo_Crank_Bolt

Watch the sunken hex recess - it is very soft. I chewed mine up and had to get a new one! :wacko:

I think the recommended pre-load (ie before you tighten the crank bolts themselves) is about 1.5Nm (do check though). I tightened mine by an additional 0.5nm and the noise disappeared. About 1800 miles since I did it and it has never returned.
 
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