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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 07-22-09, 02:45 PM   #1
Freefallman
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Light clunk when climbing

So I've been having an issue with my mountain bike. When climbing I get a light pop, clunk, or whatever when I reach the bottom of my stroke. If it's not under a heavy load (for instance flat ground) it doesn't do this. I'm wondering if it comes from the crank/bb. Everything else works fine but it's distracting. I was hoping you guys could help me identify the culprit and course of action. Thanks.
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Old 07-22-09, 07:13 PM   #2
neil0502
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You many find the following links helpful in tracking it down:

http://sheldonbrown.com/creaks.html

AND

http://www.parktool.com/repair/readhowto.asp?id=123

It's usually just a matter of patiently removing, cleaning,
re-lubing, and re-torquing fasteners until it quiets down.
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Old 07-22-09, 07:19 PM   #3
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Check your seatpost first. Remove it, grease it and reinstall then test ride it.
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Old 07-22-09, 07:22 PM   #4
Panthers007
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And check your chain for wear, and the length. Sometimes a too-long chain will do this. And look for any stiff-links.
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Old 07-22-09, 11:11 PM   #5
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Panthers: The chain should be about right. I checked it and it has about one link overlap. Also recent developments lead me to believe that it's not the chain.

So...before anyone got back to me I took it into the local coop. We tried to tighten everything up and when that didn't work we were going to check the bb. Apparently my crank arm is fused. The crank puller was stripping the threads on the crank. So we stopped and put the crank bolt back in. Now the light pop is an audible click. I think it's going to drive me mad. I'm planning on selling the bike in a few months but I want it to be in good working order. Thoughts?
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Old 07-22-09, 11:28 PM   #6
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Did you find and remove some thin-washers after you removed the crank-bolt - but BEFORE you threaded-in the crank-extractor? I'm guessing here you have a sealed-cartridge bottom-bracket?

In any event - to anyone with an Octalink or such, removing the thin-washers on either side before screwing in the crank-extractor is absolutely needed.
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Old 07-22-09, 11:32 PM   #7
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Panther....uh, no. Would you expound upon this for my education? <slaps head>
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Old 07-22-09, 11:37 PM   #8
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I'll go dig up some references...

From Park Tool on Octalink/ISIS:

Procedure for crank removal:
  1. Remove crankarm bolt and any washer inside the arm.
  2. Unthread nut from handle stud of CCP-44 or CWP-6 until the tip is flush with the nut. This allows tool to have full thread contact inside the crank.

The full article:

http://www.parktool.com/repair/readhowto.asp?id=120

So if you have an Octalink in your bike, and you left the washer in there when you tightened down the crank-extractor, you were working against yourself. Solution: Remove the washer. Now thread-in the extractor.

If you're going to buy an extractor - I recommend the CWP-7 Park Tool.


<EDIT> In the video on this subject from the BicycleTutor, you can see the washer I mention. In the video it comes out with the crank-bolt and is not specifically mentioned. I'll send a note to Alex to remedy this. While it shows it coming out, most often, in my experience, it does not come out with the bolt. It requires deliberate coaxing. Here's Alex:

http://bicycletutor.com/replace-cotterless-cranks/

Last edited by Panthers007; 07-23-09 at 12:03 AM.
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