BB creaking only under power. Ideas?
 

Hi,

This just started happening. When I spin easy, the bike is whisper quiet but as soon as I put a little bit of effort into my pedal stroke, the creaking starts. Crank and BB is Force compact with GXP BB.

Bike has an aluminum BB area (BMC Race Master) and I didn't see any visible crack. Just checked the chain ring bolts and I was able to tightened them up quite a bit. I couldn't tighten the crank arm bolt at all.

Troubleshoot other components first, process of elimination..

Try different pedals to make sure it's not the pedals that's creaking.

Tighten the headset. A loose headset can creak under power.

Tighten the QRs for the wheels. I've had those creak under power on each stroke of the pedal because they weren't tight enough, and it made me think it was the BB.

Could be seatpost / seat mount clamp or the seat rails too. Take a look at those.

Then, check the BB once those are all eliminated.

The NDS crank on your GXP BB will only go in so far, because the stepped spindle prevents it from being overtightened so it is impossible to put too much sideways pressure into the bearings. I like how foolproof and simple the GXP crank install process is.

SRAM GXP BBs have a reputation for crapping out early. I replaced mine with a Chris King BB and it has been flawless.

^this

Mine turned out to be a creaky headset.

Funny, I recently had the same experience. I could have sworn it was the BB... removed / replaced 3x to regrease and even replaced with a new BB... then, regreased and retightend the headset; voila, no more noise. Crazy.

Strange advice given how easy it is to remove and reinstall an external bearing crank. I'd suggest (assuming you have the tools and knowledge) to remove the crank and cups, check the bearings then grease everything as specified, and torque everything to spec. If the noise persists, go through LongIslandTom's list to eliminate other possibilities.

I say this because bottom brackets are so frequently the cause of the creaking noises especially those that only present themselves under power. If you were suspecting some other, less likely item that was difficult to test for (say a lugged joint in the frame) then it makes sense to look at everything else first. Similarly if you had already greased and torqued the bottom bracket twice already it would make sense to start looking elsewhere. For a first shot at the problem, might as well go right for the obvious suspect.

Ditto. Among other things, make sure the BB cups' threads are lubricated before installation. If lubing the threads makes the noise go away but it reappears soon after, try plumber's teflon "tape". One of my bikes had enough play in the threads that the cup would work loose after a while. Teflon tape took up the space and lubricated it at the same time.

I thought i had replied to this yesterday, anyhow :

The problem IMO is the stream post if you have not fix that already. If not, take it out, find a large bumper sticker made of vinyl or maybe a PDA screen protector. Cut a piece like inch wide and maybe 4 or 5 inches long and put that in the back of the seatpost. Put tiny grease in the vinyl too and put it back in. That will take care of the creack. If the creak comes back u know what to replace. I have a BMC just in case.

Options

- put some oil in the front quick release mechanism or replace it.

- Put some grease between the fork spacers.

- Put some oil between the chainring and the bolts and tight them again.

- Pedals, put some oil in the pedals bearings, have seen this aswell

- Oil in the streampost bolt wedge thing, if its dry i could start creaking.

Good luck :)

Also lube where spokes cross each other.

DPN

Thanks for all the input, everyone. When I was replacing the pedals to see if that's the culprit, the creaking noise was audible when I turned the pedal wrench to loosen the pedals. This happened on the DS and NDS. Since no weight was put on any other part of the bike when I was turning the wrench, this led me to believe it has to be either the crank or the BB.

Ultraman, being a proud BMC owner myself, I already had the Streampost wedge solution in place, and that was the first thing I checked. The noise is there when I am out of the saddle.

Put some teflon tape in the BB cups just in case.

Make sure there's plenty of grease on the pedal threads. I once spent weeks chasing a BB squeak, overhauling the BB (loose bearing type) 3 times. When I took the pedals off, the grease on the threads was dry. Greased 'em up and the squeak went away.

Is it a BB30? There's a thread about this on the road cycling forum at the moment.

I had the same issue on my supersix but thought it was my weight (I'm 225). My LBS told me that cannondale quote often don't put enough grease/lube in the BB when they assemble them a the factory. They dismantled it, packed it with grease and the noise is gone.

QR's were the culprit
 

[QUOTE=LongIslandTom;13306256]

Tighten the QRs for the wheels. I've had those creak under power on each stroke of the pedal because they weren't tight enough, and it made me think it was the BB.



Agree with LongIslandTom that many things can cause creaking. Read on another post the a bike can "cast its voice" to make you think it's creaking in one place, but really coming from another. In my case, I thought the issue was the bottom bracket, but ended up being a slightly loose hub and QR that creaked under pressure. Took a minute to tighten both and creak was gone. It's a process of elimination...