Creak from Bottom Bracket

nevica

Hello,

I have a Scott Foil 30 with SRAM ceramic GXP BB86 BB and SRAM Red BB86 GXP crank.

I have notice that when I sit on the bike and apply both brakes and then put pressure on a pedal (by trying to turn in the normal direction) I find that I get quite an initial creak. After putting on the the initial pressure on the crank the noise stops as the breaks are applied.

I have no idea what this creak could be caused by but I know it shouldn't be making this creaking noise. It's as if the bottom bracket is turning in the frame. I have checked for any play in the BB but there is non at all.

Any suggestions/ideas as to what this could be?

Thanks,

Nevica

manglier

Just to clear it up the Scott Foil 30 has a press fit BB NOT the GXP. The GXP is for threaded BB's. Having never used a press fit BB I'm sorry I can't help. Presumably you have checked the chainring bolts and eliminated the pedals as a possible source, oh! and anything to do with the saddle.

crikey

Press fit BBs are notorious for creaking; I'd guess that's the issue.

Monty Dog

Could be down to dirt or lack of lubrication, or worst case a corroded bearing(s). Remove the cranks, give everything a clean and check the bearings - they should be smooth with no grittiness - if the bearings are OK, grease all the mating surfaces and reassemble to see if that helps. If the bearings feel a little rough, you could try popping the seals and repacking with grease.

nevica

Hello,

There is absolutely nothing wrong with the bearings or crank as they are brand new.

What could be the problem?

Nevica

crikey

Look up creaking press fit BBs on google...

davmaggs

I've had this a couple of times in the past and found that I'd under tightened when fitting the BB.

thebadgerboy1982

It could be any part of the bike! Ive just been through the check this, torque that, grease it. This was on a new bike with maybe 500 miles on it. I think I've got to the bottom of it with a dry chain. The chain was degreased and cleaned with muc off, dried and lubed.
Check the normal stuff like cleats, pedals, chain, saddle, seat post bars and stem. I would think that even with a few hundred miles on the bearings, they shouldn't creak unless the cups are loose in the frame. If the bearings are the cause you should feel some resistance or grittiness when turning the cranks by hand.
Good luck!

dinyull

Loose quick release?

I recently had a creak I was utterly convinced came from BB/crank area: I took the crank and pedals off, checked the BB was tightened and cleaned/greased everything. Noise still there, until I tightened the rear wheel quick release.

rafletcher

davmaggs wrote:

I've had this a couple of times in the past and found that I'd under tightened when fitting the BB.

Difficult with a press fit BB which the BB86 is....

I doubt it's anything to do with the BB - could even be shoe/pedal interface. IF it creaks when out riding, then maybe it's the BB, but even by the standard of PF BB's it's pretty new to be creaking.

tmg

I had issue with press fit BB, in the end the bearings needed to be glued into place with loctite

I would check everything else first as mentioned above to eliminate pedals, chaintrings, cassette, seat post as a lot of creaks can resinate as if they are coming from the BB

How olds the bike? Or have you recently replaced the crank and BB? Press fit only needs to be slightly out of tolerance to get a creak

jgsi

Whats the torque setting you are using?
Running new BB30 cranks and the NDS needs nipping up after every few rides... using a bit of loctite but even so they do misbehave. Never had a problem with the alloy crankset.