Take the 2-minute tour ×
Bicycles Stack Exchange is a question and answer site for people who build and repair bicycles, people who train cycling, or commute on bicycles. It's 100% free, no registration required.

My four-year-old, carbon-framed road bike has developed a case of creaky cranks.

I only hear creaking when pedalling hard, when I pedal more softly it just sounds like it has always done.

Given the bike's age it just seems like a good idea to replace the bottom bracket. But I was wondering, once I get the old bb out, how best to prep the frame before fitting the new bb?

I've only changed BBs on steel frames before, where I applied some pretty thick grease quite liberally around the shell. But is approach applicable to carbon?

Some supplementary info: I'm riding a 2010 Giant TCR Advanced 2, with a 6700 Ultegra groupset, including hollowtech 2 cranks. I believe from the bike's spec that the bb involved is a press-fit bb, as shown on the Wiggle site. Having said that I've not taken anything off yet so this is all theoretical so far - I'm going to visit my LBS later today to get the relevant preload cap removal tool, so I can have a bit of a look around.

share|improve this question
    
What's the make and model of your frame? –  alex Jun 24 '13 at 10:12
    
One minor point: Creaking from the BB (at least in a standard setup) can be due simply to the cartridge being loose between the cups. For a glued-in BB it can probably be due to the glue being somewhat loose in spots (similar to a creaky handlebar). And of course when one hears creaks from the BB the first thing one should do is tighten the crank bolts. –  Daniel R Hicks Jun 24 '13 at 11:40
    
@alex - updated question. I'd be surprised if the make/model makes any difference to the answer though. –  PeteH Jun 24 '13 at 13:19
    
@DanielRHicks points taken, I just thought that since I was going to have to faff around down there in any case I would replace the bb while I'm at it. 4 years doesn't seem an unreasonable lifetime for a GBP30 expense. –  PeteH Jun 24 '13 at 13:22
    
@DanielRHicks - probably also worth saying that after a cursory check over the weekend, nothing appeared loose –  PeteH Jun 24 '13 at 13:37

2 Answers 2

up vote 2 down vote accepted

If it is a press fit then it is probably a BB86. You'll need a removal tool (Park BBT-90.3, I think) and a press. Get a SRAM GXP press fit bottom bracket or the equivalent Shimano part, they run about $40 USD. Knock the old one out with the removal tool and a hammer, clean the inside of the shell and press in the new one. No grease. The shells of these bottom brackets are made of a very hard plastic that will eventually loosen and start to creak.

share|improve this answer
    
thanks, you're correct it is an 86mm, in fact I confirmed it is the very one I linked to in my question (there is a choice of two, the one in the link is the better quality). I've had the new bb and the part for about a week now but haven't had time to fit it (just got back from Tour de France!) You're right about no grease also - the bb has o-ring seals between it and the frame, and comes pre-greased for through the middle (i.e. where the crank goes) –  PeteH Jul 11 '13 at 19:33
    
in previous comment for "part", read "tool". Expensive too, the Shimano tool. Park do one too which is supposed to be compatible but I didn't want to take the chance. –  PeteH Jul 11 '13 at 19:44

I've now fitted the bb, just thought I'd add a couple of details in case anyone looks this up in the future.

The answer to my actual question is that, as I removed the old bb I found grease from the original install, by the "cups". So I basically cleaned the shell as best I could, but just with a dry kitchen towel, then regreased the area.

The whole removal/installation process was done in less than half an hour. I needed two specialised tools (this threw me a little, originally I thought only one tool was required). One tool to remove the bb, a second tool to install the new one. Both Shimano and Park do the tools (in the end I ended up buying the park tool to remove the bb, and the Shimano tool to install the new one), but whichever make, you need two tools. The removal tool also needed a hammer (ouch!), the installation tool also required an 8mm allen key, but it really was straightforward to fit.

Two observations. The first was that the part that came off was not exactly what went on. I suspect this is just a "passage of time" thing, as the new part fits perfectly and was confirmed by a Giant shop as the correct part. The second.....well I was surprised just how hard I had hammer to get the old bb out. (I started off with a mallet but that was no good at all.) I suppose this could have been something to do with me thinking, every time I hit the removal tool, "I hope I don't break anything". But in the end everything was fine.

In summary:

The bottom bracket I fitted was a Shimano BB9141B. This is the better quality of two compatible bottom brackets (the other being the BB71). The differences between them seems to boild down to Ultegra versus Dura Ace.

The tool I used for removing the old bottom bracket was the Park BBT90.3. Seemed to be fine, buying the Shimano version of this tool would have cost a small fortune for some reason.

The tool I used to fit the new BB was the TL-BB12. Made the job a doddle but very expensive for something I used for half a minute!

share|improve this answer

Your Answer

 
discard

By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.