Creaking crank arm

[mynydd]

I fitted a brand new bb, with loads of grease two weeks ago. Everything was fine until yesterday, hopefully it was just me reassembling the crank, and pre load adjuster incorrectly.
Incidentally I still can't work out the concept of the pre load adjuster, and how it impacts on the bearings. Sorry for being stupid but if anyone can enlighten me I'd appreciate it, I like to know how things work.
Thanks

 

[I like Skol]

If I were you, I'd take the whole bb assembly out and thoroughly clean and re-grease and then re-assemble.
Winter's coming!

There is really nothing to grease in the Hollowtech set-up. The bearing cup threads can be greased if you are worried about them seizing into the shell and maybe grease the axle to try and stop it corroding if any moisture gathers inside the bottom of the frame (but most of this will be scraped off when inserting the axle into the bearing!) but the bearings themselves are sealed units and are pressed into the cups so cannot be greased.

 

[betty swollocks]

There is really nothing to grease in the Hollowtech set-up. The bearing cup threads can be greased if you are worried about them seizing into the shell and maybe grease the axle to try and stop it corroding if any moisture gathers inside the bottom of the frame (but most of this will be scraped off when inserting the axle into the bearing!) but the bearings themselves are sealed units and are pressed into the cups so cannot be greased.

I realise this. But the whole job'll probably take 15 mins max, so why not do it thoroughly?

 

[I like Skol]

The bearings are not designed to take any significant sidewards loading so need to be fixed in the correct position but without having too much static pressure on them. The preload adjuster is just to snug everything up on the axle enough to remove any play and no more. Over do it and you are loading an axial force on to a bearing manufactured to resist radial pressures and it will massively shorten its life expectancy. Likewise, not enough preload allows the axle to move and doubles the axial force placed on an individual bearing (the one that the crank arm butts up against at that point in the pedal stroke) and also shortens the bearing life in a similar way to over tensioning. It is a balancing act!

EDIT: This diagram might help

My Hollowtech equipped bike went through a couple of BBs in rapid succession until I realised the factory fitted spacers were too thin and the left crankarm was bottoming out on the axle splines a fraction before the bearings were being nipped up. I fitted an additional shim and after 2 BBs in less than 4k the current one is now at about 6k and going strong. I am beginning to think that the Hollowtech reputation for short lifespan might simply be due to poor installation (at the factory, bike shop or DIY).

 

[I like Skol]

I realise this. But the whole job'll probably take 15 mins max, so why not do it thoroughly?

Because it is a waste of time and you are likely to damage something in the process (i.e cross thread a bearing cup or strip one of the crank securing bolts). If it is working then leave it alone, it is not a serviceable item and does not benefit from the attention unless you know it is likely to be corroded in there.

 

[mynydd]

Thanks @I like Skol that makes a lot of sense. I have had problems on and off since the start with this bb. And have changed two in a year! Thinking about it the spacer isn't totaly snug, a fraction of a mm each side. Maybe an additional shim would sort this out ?

 

[betty swollocks]

Because it is a waste of time and you are likely to damage something in the process (i.e cross thread a bearing cup or strip one of the crank securing bolts). If it is working then leave it alone, it is not a serviceable item and does not benefit from the attention unless you know it is likely to be corroded in there.

How can it be a waste of time if it eliminates an annoying creak?
I don't want to get into a pissing contest here, but, I once had an annoying creak and I fixed it by doing what I have already suggested, so, it wasn't a waste of time.

 

[I like Skol]

How can it be a waste of time if it eliminates an annoying creak?
I don't want to get into a ****ing contest here, but, I once had an annoying creak and I fixed it by doing what I have already suggested, so, it wasn't a waste of time.

Not a pissing contest at all! You said take it out and grease it because winter is coming, not because it was creaking. I said if it isn't broken then don't fix it, while your BB was clearly badly installed in the 1st place