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Old 10-04-07, 06:50 PM   #1
rwgreenberg
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Clunk Clunk Question on a New Bike Friday

Hi all. Well my new Bike Friday New World Tourist came about 2 days ago. What a toy! I have the setup with the three chainrings in the front and 9 gears in the back. One issue stood out right away for me. Every time I shift into gear 6 or above (with gear 6 exhibiting the issue in the most obvious way) I "feel" a light discernable thud-thud or maybe a clunk-clunk (not in tune with each pedal rotation but about two per rotation and not seemingly symetrical). I can't see what is causing it when I study the rear setup on my bike stand (or the front setup for that matter). This thud thud (not loud, but more felt) is present regardless of which of the three front chainrings I am in. Maybe the cassette just needs to wear in, but I never have felt something like this on any other new bike I've had. My LBS is closed for a few days and I thought I'd have him look at it, but thought I'd say hi and ask all of you as well.
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Old 10-04-07, 08:09 PM   #2
Marrock
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Have you tried calling Bike Friday's customer service number?

From what I hear they're really good.
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Old 10-05-07, 07:30 AM   #3
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You have a sticking link in your chain. If you find it and wiggle it side to side you can free it up. A chain tool is the best way to handle the issue, but you might need to wait for your LBS to open to have them do it.
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Old 10-05-07, 11:44 AM   #4
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Thanks for the advice....sticking link?....I can't see it when watching it go around the cog slowly while inspecting things on the bike stand. I guess it could be sticking only under load, yes? I guess maybe it will go away? I guess I could spray some lube on each link and work the link a bit? Thanks again, Rich.
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Old 10-05-07, 02:14 PM   #5
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The place to watch for the stick is in the rear derailleur. If you pedal backwards you can probably find it for sure.
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Old 10-07-07, 09:24 AM   #6
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Still a Mystery

Hi. Thanks for the troubleshooting. I don't think it's a link....because I can't see it when closely inspecting it on the stand and because the problem really seems to be confined to just gear 6. I've been thinking that it may be an irregularity in the manufacture of the gear 6 (or maybe an adjoining gear)....what do you think? Maybe it will wear in?
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Old 10-07-07, 11:29 AM   #7
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Well, I would check to ensure that the cranks and pedals are on tightly first. That is a common source of clunking that can be fatal if left unattended. Other things to check include rear cones and cassette tightness. Also a good idea to have a go through with a torque wrench on all the bolts on a new bike shipped by mail.
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Old 10-07-07, 02:05 PM   #8
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Quote:
Originally Posted by pm124 View Post
Well, I would check to ensure that the cranks and pedals are on tightly first. That is a common source of clunking that can be fatal if left unattended. Other things to check include rear cones and cassette tightness. Also a good idea to have a go through with a torque wrench on all the bolts on a new bike shipped by mail.
This is a good suggestion. Although the new cranks with the external BB might not make the same sound. However, square taper and ISIS/Octalink cranks would.

Certainly could not hurt to tighten them.

Have you looked at the pedals?

However, looking at your post more carefully, I don't think that these explain why the sound only occurs in the higher gears. It makes me think that Alex is right. But just gear 6 ... interesting.
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Old 10-07-07, 03:13 PM   #9
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OK, I'll make a guess too...

Sometimes a chain master link can cause this behaviour as it passes over the cassette, especially if a wrong version was installed, such as 8sp link on 9sp chain; or also possible, a Connex link installed the wrong way round. The smaller gears are more susceptible due to smaller diameter as well as more acute chain angle.

Try to see if the clunk is synched with

a) cranks
b) wheel
c) chain
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