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I've recently bought a second hand carbon bicycle. The bottom bracket was making a creaking sound under pressure, so I took it to a shop and they put in new bearings.

But after 1 or 2 cycles it was back again. The shop sent it to a carbon frame specialist to see if it was cracked but it came back with no problems.

If I hold the bike with 1 hand and put pressure on the left pedal and crank it makes the same noise. The pedals came off my other bike and were not damaged.

Is it possible that the left crank arm itself could be cracked and causing it?

I want to get an idea if possible before I purchase a new crank arm as they are quite expensive. The only other worrying thing is that on Sheldon Browns site they say that if the left arm creaks under load that could be a sign the frame is about to fail.

Its an Sram red press fit bb30 by the way.

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    I recall having a similar problem on a mountain bike some years back where the problem turned out to be the freewheel not the bottom bracket. The solution was lots of 3in1 oil. Are you certain the sound is coming from the bottom bracket? – KeithWM Jun 26 '16 at 12:08
  • Never thought about that actually thanks , dont have a chain checker but ill have a look its a 2010 bike and its the same sram parts since then so it could be , the bike mechanic first thought it was the wheels but i have new ones now so i can rule that out thanks – Keith Jun 26 '16 at 12:16
  • When i wheel the bicycle backwards with my hands the gears actually jump onto the other gears , do you think it means the cassette is worn ? – Keith Jun 26 '16 at 13:58
  • I will just note that very often, on conventional bikes (I've never dealt with a carbon frame or press-fit BB), "creak" that actually originates in the bottom bracket is due to the BB cartridge "rocking" slightly between the not-quite-tight-enough BB cups. This is, within reason, harmless. Of course, it's also the case that "BB noise" is often due to a loose crank arm, and that is a much more serious matter. – Daniel R Hicks Jun 26 '16 at 14:34
  • I dont have the tools for the bracket but id say the shop has it the right tightness will look into it thanks, btw changed the cassette and while it stop the chain jumping when i moved the bike backwards it unfortunately didnt solve the creak , i didnt change the chain though but that would hardly make a noise ? – Keith Jun 26 '16 at 15:45
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Just a guess, is the bike a Cervelo? They are notorious for creaking, but are hardly unique.

I agree with the above comment about bearing movement inside of the frame. It is maddening. There are several ways to solve this:

Instructions: Do not go back to the LBS you've used earlier. Nothing mean but they seem to lack the experience to figure this out, unless they just like selling you stuff.

Keep your cash. I seriously doubt that your crankarm is damaged. Even if I am wrong you can buy a new Ultegra crankset for far less than what you are hinting at for a single crankarm.

If you changed the cassette (which are pricey) you should also change the chain (which are relatively cheap). They wear together. It's cheap insurance, but will have nothing to do with your creaking noise.

Solutions: If it is the BB30 shifting inside of the bb shell there are several options. Most frame manufacturers have what are essentially shims that press into the shell, and then the bearing presses into them. There are exceptions, and it is less common on the newest bikes, but they do exist for this reason. A good LBS will know and understand this.

If it is a direct fit into the frame there is a locktite product that will fill the gap, solidify and end your creaking nightmare. It will likely void the warranty, but that warranty went out the window a long time ago. I've never used on a bike (but have on other situations), it but have read good things about it.

Chainring bolts. Are they loose? Have you taken them off, cleaned them carefully and used thread locker on them? They can make some strange noises as you pedal.

And on the off chance, how tight are the quick releases levers on the wheels? I had a Bianchi that had the classic BB noises and behaviors. I was in the middle of nowhere and confused to how this could happen so abruptly. On a whim I tightened the rear wheel really tight, and it went away. Only with those wheels and that bike together did I have that problem.

Good luck. Always check the cheapest and easiest stuff first.

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  • Its a boardman air 9.8 team issued with united healthcare on it , some of the bolts were very loose like less than 3 nm so i tightened them up tight enough , didnt clean um though so i should try that . Wheels are new mavics and were incredibly expensive as it eas believed the older wheels were the problem – Keith Jun 26 '16 at 18:07
  • Se.Ses only when i put my foot on the left pedal that this happens it doesnt on the right at all . Yeah although the shop is very expensive and have all the top end stuff could be worth trying another shop just to see . I have a fsa bb 30 press fit crankset on my other bike , would i be able to switch the left crank arm on it just to see if it is or will the sram red crank arm be a different match ? Both are press fit bb30 – Keith Jun 26 '16 at 18:07
  • Hi Keith. Who makes both cranksets? That will determine interchangeability. Since it is only on the left side, it could be just the left bearing that is moving around. Also, some companies (FSA in particular) used a "top hat" spacer between the bearing and the crankaxle. It would wear out in short order and cause knocking and some creaking. Let me know how makes the crank and I can guide you a bit more. But push comes to shove, they are going to have to be from the same company and groupset. – user26705 Jun 26 '16 at 21:19
  • Sram red press fit bottom bracket 30 2012 model i think is the problem one and FSA Gossamer compact 50/34 is the one i want to try put on , would both crank arms fit each other just to try test and see if its the problem? Sram red chainset is a few hundred euro couldnt afford to buy it if its not the problem – Keith Jun 26 '16 at 22:26
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Remember, there are two bearings in the BB, and it is possible to have one go bad/move around while the other is steady. Bearings can shift in their housing, rust on their external cups, rust internally, you name it. BikeRadar has an excellent article on them:

http://www.bikeradar.com/us/gear/article/workshop-how-to-service-bb30-press-fit-bottom-brackets-29544/

In the end you need a second opinion from a trusty shop.

One last obvious thing I haven't asked is if you have removed the bolt that presses the left crankarm to the axle. I recommend you clean both the bolt, inside of the crankarm and the internal threads of the axle, regrease and reinstall snug to tight. The fact that the left side immediately makes noise is a bit odd as my experience is that bearings make their weird noises under the changes in load while pedaling. Check out the article, and good luck. Let me know what you find.

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  • Theres a lot of tools needed and i just dont have the money at the moment took it into bike shop though so will report back with any news thanks for the input though – Keith Jun 27 '16 at 11:27
  • Turned out it was the left crank arm after all , glad it is fixed now . Only 1 more question what measurement or type of crankset do i need to fit a press fit bb 30 , i see things like gxp 175 mm and other measurements which one or ones will fit bb 30 press fit ? Thanks – Keith Jun 30 '16 at 8:11
  • m.ebay.ie/itm/… will this gxp size fit my pf bb 30 ? – Keith Jun 30 '16 at 9:56
  • Wow. Well, that is a first. I'm not married to my answers but I still have to wonder how an arm goes bad. Who would of thought. Now compatibility between standards (and there are a lot of standards) is tricky. What you need to look for is spindle diameter of the crankset and the internal diameter of the PF30 BB. Sram/Truvativ make the GXP BB and I like it a lot. But I cannnot give you a 100% sure answer as I don't know those things. I would encourage you to google away, and perhaps even consider a much cheaper but supremely capable Shimano 105 crankset and new BB to fit, for a lot less. Luck! – user26705 Jul 1 '16 at 11:22
  • Yeah even the shop was baffled i kept saying it was coming from the left side i asked him could it be the crankset itself and he said theyd never be broken , when i got the bike though there was no grease in the bracket which probably led to if the owner seemed to neglect his bike . A lot of brackets you can get adaptets to fit into your own bracket but i found a force chainset for 245 , apparently bb30 will fit its gxp that is a different one. Yeah i was looking at that and ultegra set but that is a hollowtech ii something bracket which would require a adapter , thanks a lot for the help – Keith Jul 4 '16 at 8:44

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