Take the 2-minute tour ×
Bicycles Stack Exchange is a question and answer site for people who build and repair bicycles, people who train cycling, or commute on bicycles. It's 100% free, no registration required.

My bike has been ridden 4 months / 2000 miles and is no longer completely quiet.

About a month ago I noticed a whispering noise like a wire brush sliding across a cymbal. It happens on the power-down-stroke, in any/every gear, so I think it must be the 'bottom bracket' or something close to that. A noise (creaking) is now happening on both strokes (both feet).

No one mentioned bearings when I asked How much maintenance?

A co-worker said it needs fixing when the pedals are 'loose' (which they aren't).

Can it wait another 2 months / 1000 miles or so until its first regularly-scheduled twice-annual in-LBS service?

Or is it a case of "an ounce of prevention is worth a pound of cure," and I should ask someone to maintain it a.s.a.p. before it gets (irreparably) worse?

Do they even need maintenance, or are they just replaced sometimes?

share|improve this question
    
Possible duplicates include Bearing replacement and upgrade? and How long will it take to replace the bearings in my bottom bracket? which suggest that maintenance is necessary. –  ChrisW Jul 14 '11 at 2:16
    
Why are you opening up a question and then saying it may duplicate much of what's in two other questions? (Edited your title to help differentiate the question from those other two.) –  Neil Fein Jul 14 '11 at 5:21
    
@Neil - I'm opening a question because I want to know, and the answers in the other two don't answer my question. It's possible that those other questions are by and for experts, and presume background knowledge which I don't have. –  ChrisW Jul 14 '11 at 10:42
    
@Neil Fein: Is there a better way to handle this situation? –  zenbike Jul 14 '11 at 14:36
    
"... a whispering noise like a wire brush sliding across a cymbal... Do you have a jazz drummer in your bottom bracket? –  user313 Jul 14 '11 at 23:40
show 1 more comment

4 Answers

up vote 3 down vote accepted

Quoted from the Park Tool site:

There is a fairly simple test to determine if the bottom bracket bearing is worn out. Shift the chain to the inner most rear sprockets front and rear. Drop the chain off the smallest front ring, and arrange it so it will not strike the chainrings. Spin the crank while holding the bike with one hand. If you feel an obvious rumbling or grinding feeling, the bearing are worn out and the unit should be replaced. Very worn bottom brackets will actually make a grinding noise.

I'd fix it now if you're getting these symptoms. Grinding is a sign of bicycle arthritis and is easily solved with new bearings. Bearings wear out and can lead to damage if not replaced.

share|improve this answer
add comment

Don't assume that it's the BB. When you press down on the pedals, you're actually putting stress on many different parts of the bike, and any one of them could be making noise.

Your description of the sound makes me think of the chain. Try lubing the chain, and see if the noise goes away.

share|improve this answer
add comment

If your bottom bracket is going, then there will probably be some play in it - you can easily check for this by holding one pedal in each hand and pushing/pulling to pivot the cranks around the bottom bracket. First try pulling both pedals away from the frame then push them both towards the frame - if you feel any movement then your bottom bracket probably needs replacing.

You can do the same test on your pedals, which are another common source of noise from that part of the bike. Start with the pedal horizontal and twist left and right, keeping the pedal horizontal. I find pedals commonly have a little bit of play so judging it is a bit more down to experience, but too much movement means time for new pedals.

Neither of these tests can prove that the part is working perfectly, but finding play is a good sign that the parts are on the way out.

share|improve this answer
    
Thank you. Is this Bottom Bracket Adjustment video, for example, a good and complete illustration of what you're saying? –  ChrisW Jul 14 '11 at 12:44
add comment

There are several possible causes of noises you can get from your bottom bracket.

  • Bad bottom-bracket bearings
  • Bad pedal bearings
  • Loose crank arms
  • Loose bottom-bracket cartridge
  • Loose chainrings

Of these the loose crank arm (which may be silent or may be accompanied by a creak on each stroke) is probably the one needing the most immediate attention, since riding even 10 miles with a loose crank arm is enough to destroy the crank arm and crank shaft. So you should either check that the crank arms are tight yourself (by torquing the fixing bolts appropriately) or have a bike shop do it.

After that, I've experienced most of the above, but probably the bad (or simply dirty) pedal bearings more than anything else. Pedal bearings seem to pick up dirt faster than any other bearing on the bike (especially when offroad or riding on packed gravel), and unless they are well sealed may need regular disassembly and regreasing. And I've had new, sealed pedals develop noises in as little as 200 miles (though the set I have now have been fine for probably 8000 miles, knock wood).

I did have the bottom bracket cartridge on my current bike start making noise after about 5000 miles (more of an occasional click than grinding). On disassembly the (Shimano) cartridge was found to be badly rusted (even though the bike is only left out in the rain when commuting). Replaced it with a SS Phil Woods unit.

The BB bearings went out on my old Nishiki after a few thousand miles, and on inspection it appeared that the cups had been poorly machined to begin with. (This was maybe 18 years ago.) Replaced the loose bearings with a Performance cartridge.

A bike with only 2000 miles on it should not need any bearing service, unless it's been seriously exposed to bad weather or other severe conditions. But note that 2000 miles is about the expected life of a chain, and yours is probably due for replacement.

share|improve this answer
    
I was typing an answer that covered the same main points when I saw the red bar notice that the question had just been answered. That said, if the bike is that new, your bike may very well be under warranty, so take it in as soon as possible. –  thajigisup Jul 14 '11 at 3:19
    
Are you saying that, with this symptom, the only/main thing I should do is ask a shop to check the torque on the crank arm's fixing bolts? Or if it has already survived 10 miles without being obviously destroyed, can I assume that that has been alright? –  ChrisW Jul 14 '11 at 11:48
    
Are there other tests/diagnostics/maintenance procedures I should know, to determine the cause/origin of the noise? You say that it shouldn't need service after only 2000 miles. Given that it is making a little noise, are you suggesting that a little noise shouldn't need service, or that it shouldn't be making a little noise? The pedals are Shimano PD-A530. The bike has been stored outside all day (weekdays) and in all night. –  ChrisW Jul 14 '11 at 11:49
    
@thajigisup - There's a warranty against manufacturing defects (not normal wear). The LBS offers free (i.e. you pay for parts but not labour) service 2 times/year for the first two years; the first service is due in about two months from now. –  ChrisW Jul 14 '11 at 11:52
1  
Besides checking the crank, a normal service would include checking the bearings (crank, pedal, wheel, and headset) for play or any sign of binding. Also, as a part of normal service, the derailer adjustments would be fine-tuned, and the brake action checked/adjusted. Also, the degree of chain stretch would be checked. –  Daniel R Hicks Jul 14 '11 at 14:47
show 2 more comments

Your Answer

 
discard

By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.