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Discussion Starter #1
I poked around the www for tips on BB creaking, but nothing looked promising.

Equipment:
I know there's been a lot of changes since the last time I opened up a BB, but this looks familiar to me: Threaded shell, fixed cup on chainring side, adjustable cup and lockring on other side, square taper. No specifics known, but it's on a SRAM/Truvativ crankset, for what it's worth.

Symptom:
Creaking sound under torque. Doesn't require much to bring it on (moderate torque sounds about the same as a hard climb). The creak is abrupt, almost like a click, with one distinct sound (i.e. it's not like a squeaky door hinge where you keep hearing the sound as you press on it; it's a one-and-done phenomenon until the next pass). It's hard to describe sounds, but I think some might call it a ping. Sound started fairly quiet and infrequent, and quickly became louder and more frequent in the course of perhaps 50-80 miles.

Troubleshooting:
Cranks are well torqued.
Bearings seem to be fairly well adjusted. Maybe a smidge tighter than ideal, but no binding, no grinding, seems good enough when I spin by hand w/o chain.
To isolate BB as cause of noise, I rotated crank arm until right next to seat tube, and pressed crank toward seat tube, or pulled crank away from seat tube (either direction sounds about the same). I was careful to apply pressure only to seat tube and crank arm, to isolate BB as cause. It takes a fair amount of force (a frail woman or an elderly man would likely be unable to produce the sound by hand).

Observation regarding repeatability:
Once the BB makes that single creak, and pressure is released, it won't make the sound again until the BB is torqued the other direction (either by pulling on the crank arm in the opposite direction, or putting weight on the opposite pedal). In other words, the sound can not be summoned multiple times by simply applying force, relaxing, and then applying the same force. An opposite force is required to summon the next creak. Incidentally, this isn't intermittent. I can produce this sound X times in X attempts.

If I were to imagine what a failing weld would sound like, this is pretty much it, except that I would think that would produce a scenario where the frame would return to neutral after each trial, so the sound could be produced over and over with the same force (see paragraph above). Anyway, no visual evidence of weld failure.

I don't think the problem is at the spindle/arm interface (square taper). Reason: It would be really weird for both sides to develop the symptom at the same time, and then progress (get worse) in synch. Therefore, I suspect an internal problem.

There's not a lot to a BB. Spindle, bearings, two cups, lockring. I've never seen a BB fail, or even cause problems. I'm mystified. The cups are removed with a splined tool (I imagine it looks like a large splined freewheel remover). I don't have the tool. I'm not averse to buying it and getting in there, but unless there's a smoking gun in there, I wouldn't even know what to look for, other than a general condition inspection.

Sorry this is so long, but I think that's better than being vague and then everybody asks 20 questions.
 

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The 4 square taper BB's you can buy nowadays are just poor quality.
Especially if you not just ride a city bike around town, or if you are sensitive to weird noises.
I rode 3x and 1x drivtrains with square taper cranks for almost 2 years and had not a single BB that didn't creak, or sounded like sandpaper after a short time.
Heck, I even had 2 brand new Shimano square bb's that had the "sounds like sand in the bearings" noises out of the box.
When I started riding more aggressively on my local trails the bb's even failed.
In the end I switched to a proper 2 piece crankset with 24mm axle.

You can of course just buy a new square bb. But again, todays square bb's are just not good anymore.
 

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77 times out of 100 my creaky square taper or octalink bottom brackets are brought to silence by pulling the crank arms, cleaning the interface thoroughly, greasing lightly and reassembling. 22 times out of 100 my squeaky taper or octalink bottom bracket are brought to silence by pulling the crank arms and cups and cleaning them thoroughly and reassembling with loctite on thee cups and grease on the interface between crank arm and spindle. I don't think I've ever had a bottom bracket with bad bearings actually cause a creak. And a poorly adjusted square tape or octalink bottom brackets adjustment/bearing play/smoothness can only be judged when installed with the crank arms off.
 
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