Bicycle Mechanics - Creaking noises and Rear Derailer
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07-15-02, 06:04 PM
First of all I have a major problem with a creaking noise coming from my bottom bracket. Ive taken it all apart and replaced the bearing, but it is still making a noise (it is not the peddles). How tight should the lock bolt bit be (im not sure what you call it). Could the problem be with the cranks?
Also sometimes when going round corners fast the Rear Derailer shudders, Why is the happening? their is a little bit of play in the rear wheel, would this have anything to do with it?
Many thanks in advance.
Particularly if only one crank creaks, retorque its mounting bolt.
If you have a traditional open-bearing BB, inspect the spindle and cups for gouges, and try replacing the ball bearings themselves. If you have a cartridge-style BB, be sure to grease the threads of the retainers.
Readjust your rear axle bearing cones to eliminate the slop. (See an earlier thread regarding controversial proper adjustment techniques for QR wheels. I still favor leaving a small amount of slop, on the theory that clamping the QR skewer will force the cones to move minutely toward one another.)
07-15-02, 09:26 PM
I gave some possible causes and solutions for creaks here: http://www.bikeforums.net/showthread.php?s=&threadid=11606
Can you tell in more detail about the parts on your bike? In general you would want about 25 ft-lbs. of torque on the bolts that hold the cranks on, if they use conventional square tapered spindles (http://www.excelsports.com/item.asp?major=1&minor=6&description=600+Bottom+Bracket&vendorCode=SHIM) or about 35 ft-lbs. on splined spindles (http://www.excelsports.com/item.asp?major=1&minor=6&description=Ultegra+Bottom+Bracket&vendorCode=SHIM), unless the manufacturer of the parts says otherwise.
As for the wobbling problem, if you pick up the rear of the bike and push the rim back and forth at the brake, is there looseness? If so, better get it adjusted. There are some instructions on Park Tool's website (http://www.parktool.com/repair_help/howfix_hub.shtml) showing what you need and how to proceed, or your LBS can do the deed if you would rather.
If some of that is wide of the mark, give some clarification and we can brainstorm some more. :)
07-16-02, 12:07 AM
Are you SURE it's the bottom bracket creaking? I've had creaks from everything from the seatpost to my aerobars and it sometimes is very hard to tell exactly where the noise is coming from.
07-16-02, 08:26 AM
Creaking bikes can drive one mad. Your problem may be similar to the one I just experienced Since you describe a looseness in the rear wheel, it would be worth checking the hub bearings, if only to eliminate this from the investigation. Check the cones for pitting - these bearings work very hard - nearly as hard as the bottom bracket.
- I thought it was the bottom bracket, so had the LBS replace the sealed unit, but the problem was still there. I'd only just serviced the rear hub bearings, but they were so poorly sealed that water had got in and turned the grease into a rusty, watery mess and the left side cone was damaged. A replacement cone, and careful reassembly of the hub fixed the problem (much to my relief. I have tried to improve the hub sealing since, see my "Shimano Sora Hub Seal Experiment" elsewhere, and was recommended some teflon loaded grease by the bike shop - this should help repel water. Luckily, having had the bottom bracket replaced was not such a waste, the original was so badly seized in the frame that it took the LBS guys 3 days to tease it carefully from the frame (bike is 18 months old!). That was worth sorting out before it got worse...
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