Bottom Bracket

thekgb

hi there,

i've read some of the archives about BB creak, and done some troubleshooting, but here is my problem. My BB/crankset only creaks when the RPMs are low. IOW, mainly when i'm grinding up a hill, or going from a stop to a start. Once i'm up and running it's fine. Sprinted with it yesterday: no noise. Did hard group ride: no noise. But starting after a stop sign, there it was.

I just put the crankset/BB together a few weeks ago, and i knew the BB was slightly used (say 1000miles). I didn't have a torque wrench but i tightened it enough so that there was no wobble/play (still isn't any play) and it rode fine. It was fine until my race last weekend, and now it's makes this creak/grinding noise. I would describe it as a click with a slight grinding sound which happens in rhythm with my downstroke on the non-drive side.

I thorougly applied grease to both cups and all areas of the BB/crankset. I altered my limit screws on the front derauilleur thinking maybe that when i'm in low rpm im usually struggling up a hill in my lowest gear and maybe the chain was rubbing. that didn't help.

Is the BB failing? is it typical to only hear the creak in low rpm circumstances? can it possibly be over-tight?

any help appreciated.

Mike

kdelong

I'm not sure that I want to talk to you as I might end up in Lubyanka Prison, but anyway, are you using a cup and cone BB or a cartridge BB? You mentioned that you applied grease to both cups.

From your description it appears that you don't hear the sound when you are spinning put you do when you are pumping. It may be a pedal problem so you might want to try a different set of pedals and see if it goes away. It may be a crack in the frame so you will definitely want to get it fixed and not just ignore it. I doubt that the BB is failing. 1K miles is not a lot for a BB. It is possible that you do have it overtight and that the only reason that you hear it at low RPMs is because it is masked at higher RPMs.

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oldbobcat

When you're grinding you exert more stress on the bearings. If this is a traditional internal bearing, have your BB shell faced. Torquing down the right-hand cup and the left-hand lock ring on a BB shell whose end surfaces are not square can actually distort the shell, preventing the balls from rolling true in their races.

Facing squares the BB shell ends and is not as critical for external bearings.

Albert 50

Tighten the bejeezus out of it again. Then tighten it some more.

Solanog

I would check the pedals, I'm getting something similar in my MB and I think it comes from the pedal, the left one. I've had no time to check it but I will at least put some grease on them.

kdelong

Just checked my torque wrench. Couldn't find the "Bejeezus" setting anywhere! Exactly how may foot pounds is that, or would it be measured in mile tons?

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Lama

I was waiting for someone to pick up on that bit of Aussie talk

FWIW - you dont need a talk wrench when going to the 'bejeezus' setting - just a really really long spanner - and stand on it

oldbobcat

Never tightened the bejeezus out of my bottom bracket cups. Once or twice accidentally overtightened a little and the crank wouldn't turn as freely.

Tighten to the point where it doesn't wobble or clunk, then overtighten a smidgen before torquing down on the lockring. The lockring will pull the left cup out slightly.

artemidorus

He's probably not using a traditional BB.

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Albert 50

It appears to me that the outboard type cups are notorious for crick, cricken. Listening to even a slight constant every crank rotation crick is so annoying even when it is on a bike riding near you.
The handle that comes on the BB tool [that I have] is short. You should be able to get it tight enough by hand but you may need a glove. The obvious answer is a torque wrench I wouldn't recommend using any sort of leverage device like a piece of water pipe to tighten any BB. Using pipe to loosen a stubborn one should be fine.
Disclaimer:- Should you decide to listen or take notice of anything I say here or anywhere else for that mater do so at your own peril

thekgb

No i don't think i am using a traditional one, however my experience with them is limited. This one is for a SRAM force and is the type where the bearing are on the outer portion and they can be pulled off a center plastic piece (which the crank arm slides though to the other side).

Just to update you: I took the BB out on Saturday. I noticed when i took it out that the cup things that went into the frame (which holds the bearing and the plastic thing) were a bit un-tight (not loose). I brought it to the LBS where after having 2 or 3 guys handle it, look at it, rotate the bearing parts...they all came to the conclusion that there was no clear signs that it needed to be replaced. they covered it with teflon tape and i re-installed it with lots of bejeezus style torque. the guy at the LBS said if you didn't make a funny face it's not tight enough. then I HEAVILY greased all parts. I took it out for a short ride up a steep hill and in the end it still creaked!?

However, i did notice that 2 of the chain ring bolts were loose so i tightened them. I haven't had a chance to ride it since, but i'm commuting home on it tonight with a 45 min FTP interval, so that should give me an answer.

-Mike

Solanog

I checked and lubed the pedals, I can't believe I really notice the difference, they felt really smooth and no squeaks.

Yojimbo_

Check the pedals again, as I bet this is where your problem is.

I had a similar problem last year - brand new bike with a creak that appeared to be coming from the bottom bracket. The creak correlated with my pedals being in a certain position, and if I unloaded one pedal while turning the creak went away.

Luckily I had just bought a set of identical used pedals for my other bike, so I was able to replace the pedal I suspected with a different one. And the creak went away.

Good luck to you.

artemidorus

Most of my clicks in phase with the cranks turning have come from the pedals or cleats.

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