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Bicycle Mechanics Broken bottom bracket? Tacoed wheel? If you're having problems with your bicycle, or just need help fixing a flat, drop in here for the latest on bicycle mechanics & bicycle maintenance.

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Old 07-11-12, 03:56 PM   #1
SEAtrain
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Creaking noise

I'm working on a buddy's bike with a creaking noise which sounds like it might be from the bottom bracket. It's a somewhat older durace crank and bottom bracket with external bearings (maybe circa 2004-ish). From what I understand, he fought it last year but it's starting to worsen.

I observe a lower frequency almost ticking noise when standing on the pedals. It's creaking on on both downstrokes. Shifting body weight to the rear reduces the noise and sitting on the saddle seems to eliminate it. At least, with the short bit of riding I did to evaluate the noise.

Today I disassembled the crank and bottom bracket. The crank end cap was WAY over-torqued. The park bbt-9 plastic end cap tool wasn't up to the task of loosening the end cap. The bearings turn without grit or grinding. I noticed the drive side bearings don't turn quite as freely but there is no binding.

I reassembled everything and properly torqued the crank end cap and bolts. The creaking continues and I'm uncertain what to try next.

Could this still be a result of bearing problems even though the feel OK? Something has to be moving on me and I just don't know what it might be.

FYI- I didn't find any headset play and I tried swapping pedals. The creaking noise doesn't seem to change if I lighten pressure on the handle bars.

Ideas would be appreciated. I don't know if I've missed something with the crank/bottom bracket or if I need to look elsewhere.
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Old 07-11-12, 04:13 PM   #2
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FYI- Shimano FC-7800 crank. Not sure about the external bearings as I returned the bike until I can figure out what to do next.
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Old 07-27-12, 02:31 PM   #3
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The mysterious creaking continues. It creaks when standing and it is synchronous with both down strokes.

So far, I have installed a new bottom bracket and swapped wheels & pedals. I'm not sure what to try next. I did not see clear evidence that the frame was faced when I installed the BB.

Facing is about all I can think to try. Any other ideas?
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Old 07-27-12, 02:38 PM   #4
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I forgot one other detail for consideration. The crank spec sheet details a "stopper plate" for the non-drive side which is missing. Not sure of it's purpose.

http://techdocs.shimano.com/media/te...9830605111.pdf
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Old 05-05-13, 10:45 AM   #5
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Seatrain did you ever get to the bottom of this? I have precisely the same problem with the same 7800 chainset. I've changed the bottom bracket. I've changed all the chainring bolts. Checked the crank pinch bolts. Checked the pedals. Tried different wheels. Taken apart the chris king headset. Checked the stem handlebar connection. Just creaking, both downstrokes only when standing. Titanium serotta frame so doubt that's cracked. Looking for a eureka moment!
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Old 05-05-13, 12:36 PM   #6
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Quote:
Originally Posted by Heavy Dragoon View Post
Seatrain did you ever get to the bottom of this? I have precisely the same problem with the same 7800 chainset. I've changed the bottom bracket. I've changed all the chainring bolts. Checked the crank pinch bolts. Checked the pedals. Tried different wheels. Taken apart the chris king headset. Checked the stem handlebar connection. Just creaking, both downstrokes only when standing. Titanium serotta frame so doubt that's cracked. Looking for a eureka moment!
No, I never found the root cause. It taunts me everytime I ride with my buddy, too. Something is moving and I haven't figured it out!
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Old 05-06-13, 04:47 AM   #7
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Damn! Taunting me too. I generally pride myself on the maintainance and general state of bike and this has become so annoying I'm using a different bike. The thought of taking it to a shimano specialist mechanic as a last resort and him going through all the steps you and I have already done is galling. I spoke to one such shimano expert mechanic at cycle surgery near london bridge, he suggested making sure that the pinch bolts on the left crank had been done up progressively, rather than one then the other. Tried that, no joy. If I had to guess again I think it might be the chainring bolts. I recently changed them all and put on new rings at the same time. I used this guide for the torque http://bicycletutor.com/torque-speci...ns/#Chainrings and have subsequently tried increasing the torque. Still no joy but it is the obvious place given the slightly increase leaning of the bike when you stand up to pedal. I'll let you know if I get anywhere.
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Old 05-23-13, 02:08 PM   #8
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Right, after humbly submitting to the expert here is the solution and I confirm it is utterly and completed sorted. Slight increase in torque on left BB bearing (octalink) and I think importantly the use of copper grease instead of normal lubricant grease. Also slight increase in the tension of the screw that holds the left hand crank close to the bottom bracket, the one that's done up hand tight with the plastic star shaped tool. Both pedals copper greased too although I think they weren't the problem. Copper grease is it seems better for anti seize rather than lubrication use. The mechanic that sorted this felt that he found the copper grease slightly more effective and needed on titanium frames. Now you have the answer. Hope it solves your prob too seatrain, let me know.
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Old 05-23-13, 02:15 PM   #9
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http://www.youtube.com/watch?v=ZRVvQUWraTs Here's the stuff he used. I think it looks exactly like ordinary copper grease which you can get from Halfords or any car parts supplier.
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