PressFit BB and/or a creaking frame advice needed

gussyboy81

Firstly I hate press fit bottom brackets!!

Now thats out of the way I'm looking for some advice with my press fit BB. I've got a carbon frame with a Shimano BB91-41 and I've just had a new one installed and after two weeks of silence the annoy noises are starting to come aloud again. I was informed by the guy who replaced my old BB that it was in fact broken and it was it that was making all the noises. I'm not certain whats creating the noises this time but it sounds exactly the same as before. Surely the BB isn't broken, so is it fitted incorrectly?

I've read about using a Loctite in the cups to remove noise, but I'm not sure if thats a wise suggestion. I've also looked into replacing the Shimano BB with something more expensive like Rotor steel BB (http://www.rotoruk.co.uk/btmbrackets/pressfit-steel.php), but I'm worried that could be an expensive cost if its in fact the frame making the noise.

Has anyone got any suggestions on what steps i can take to resolve my pain. I'm aware everyone moans about PressFit BB's so surely someone has found a solution?

Finally its it worth my buying the tools to remove and fit a BB myself? Any ideas on how you clean the bearings and the BB? I've not found anything helpful on the web.

Thanks

Rightarmbad

That bottom bracket is one of the most reliably noiseless BB's there are.
What was broken on the original?
Sounds truly sus to me.

Has probably been pressed in slightly crooked and maybe not even greased.

Every press fit 41mm BB I have ever seen give problems showed marks on the BB shell from not being pressed in square and distorting the shell.
Hell, I even see shops pressing both bearings in at the same time and the thing rocking it's way in until it finally squares up as it hits home.

Use em right and they are beautiful, long lasting and silent.

gussyboy81

[url=http://www.bikeradar.com/forums/viewtopic.php?p=19666957#p19666957]Rightarmbad[/url] wrote:

That bottom bracket is one of the most reliably noiseless BB's there are.
What was broken on the original?
Sounds truly sus to me.

Has probably been pressed in slightly crooked and maybe not even greased.

Every press fit 41mm BB I have ever seen give problems showed marks on the BB shell from not being pressed in square and distorting the shell.
Hell, I even see shops pressing both bearings in at the same time and the thing rocking it's way in until it finally squares up as it hits home.

Use em right and they are beautiful, long lasting and silent.

He never explained what was wrong with the original, he did say it took a long time to remove as it was "Really stuck in there". He's a local man to me and I've gained a lot of trust in him as a mechanic so I'm sure he's not giving my a pack of lies.

He also explained how he fitted the new one as I was interested, but he never mentioned grease etc.

Any suggestions what to do? Maybe ask him to remove it and put it back in to make sure its in straight? What about one of those rotor BB's I've been told they've far better than the Shimano plastic versions.

keef66

As far as I can tell the Shimano press-fit BBs are among the most reliable. The engineering grade plastic bearing cups ensure a snug fit even if the BB shell is slightly imperfect. I have one in a carbon frame and it's completely silent after 2 years.

I wouldn't go using Loctite in a carbon BB shell unless the manufacturer specifically recommends it. You could bugger the frame next time you need to remove it.

What does it feel like if you drop the chain onto the BB and spin the cranks? Smooth / silent? Can you push the cranks sideways? Is it stiff at all?

IME creaks in a carbon frame can be difficult to track down. Saddle rails / clamp / seatpost / bars / stem / headset / QR skewers / dropouts /chainring bolts / pedals / cleats and even bottle cage bolts can cause creaks which sound like they are coming from somewhere else...

gussyboy81

[url=http://www.bikeradar.com/forums/viewtopic.php?p=19667114#p19667114]keef66[/url] wrote:

As far as I can tell the Shimano press-fit BBs are among the most reliable. The engineering grade plastic bearing cups ensure a snug fit even if the BB shell is slightly imperfect. I have one in a carbon frame and it's completely silent after 2 years.

I wouldn't go using Loctite in a carbon BB shell unless the manufacturer specifically recommends it. You could bugger the frame next time you need to remove it.

What does it feel like if you drop the chain onto the BB and spin the cranks? Smooth / silent? Can you push the cranks sideways? Is it stiff at all?

IME creaks in a carbon frame can be difficult to track down. Saddle rails / clamp / seatpost / bars / stem / headset / QR skewers / dropouts /chainring bolts / pedals / cleats and even bottle cage bolts can cause creaks which sound like they are coming from somewhere else...

Thanks for the feedback I'm going to give my bike a once over this weekend to see if i can find out what the cause is. The noise is getting louder and starting to drive me crazy, it really sounds like its from around the BB area.

gussyboy81

Finally fixed it, turned out to be the quick release on the rear wheel. Bit of grease soon sorted it out, total delight to ride a quite bike once again.

keef66

Thanks for the update. Always nice to hear how a problem was resolved; helps when giving advice in the future.