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Old 09-12-09, 06:32 PM   #1
TheCROW
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Chain noise, help!

Hey All,
I'm having a problem and since I'm new to bike mechanics, my only solutions is to ask for your help.
My last resort would be to take the bike to my LBS but they are a bit far. Here goes:
I recently got a brand new Trek 3700, it has like 100-150km. I'm started noticing a metallic noise while pedalling. I narrowd it down to the chain rubbing on the front derailer cage, cos the noise increases as I shift to the smallest rear sprocket. The shifting is very normal and I'm not having any problems besides that. I called and explained the problem to my mechanic and he said I should try loosening the barrel adjuster on the shifter. I still haven't tried it, thought I'd run it by you guys first
What do you advise?
Thank you so much.

Worth to note that last week, before the noise appeared, the chain derailed and got caught under the FD cage and a link got bent a little bit. I was far from home but was able to get my hands on a pair of pliers so I straightened it and rode back home. The next day I took the bike to my LBS and they checked it and tuned it, they said no need to change the chain cos it seemed straight and no bent link was found.
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Old 09-12-09, 06:35 PM   #2
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Cables alway stretch on new bikes and you have to adjust them.
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Old 09-12-09, 06:58 PM   #3
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Cables alway stretch on new bikes and you have to adjust them.
That's quite the assumption to make given the symptoms.

OP: If you want to learn how to do a full f.d adjustment go here: http://www.parktool.com/repair/readhowto.asp?id=75
Or take it back to your LBS.
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Old 09-12-09, 07:21 PM   #4
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Thanks for the link.
I sure would like to learn how to do this.
So I guess I have to fiddle with the H screw? Any more info?
Thanks.
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Old 09-12-09, 07:22 PM   #5
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Thanks for the link.
I sure would like to learn how to do this.
So I guess I have to fiddle with the H screw? Any more info?
Thanks.
Do the full procedure. Do not skip steps.
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Old 09-12-09, 07:38 PM   #6
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I will.
Thanks for your help.
I'll let you know how it turns out
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Old 09-12-09, 08:12 PM   #7
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Do the full procedure. Do not skip steps.

+2
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Old 09-13-09, 11:42 AM   #8
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Still no cigar... I'm beginning to think I must have a bent chain link somewhere.... Is there any way I can check for this?
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Old 09-13-09, 04:08 PM   #9
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You need to lift the rear and look at the chain as it goes across the cassette. You should see a bent link at this point on the drive train.
Ten wheels was right. On a new bike or a new cable there will be a little bit of streach and you can adjust the cable tension at the shifter by unscrewing it.
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Old 09-13-09, 04:13 PM   #10
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Still no cigar... I'm beginning to think I must have a bent chain link somewhere.... Is there any way I can check for this?
Could you explain, what exactly the problem is before we start random speculating?
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Old 09-13-09, 04:13 PM   #11
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You need to lift the rear and look at the chain as it goes across the cassette. You should see a bent link at this point on the drive train.
Ten wheels was right. On a new bike or a new cable there will be a little bit of streach and you can adjust the cable tension at the shifter by unscrewing it.
No he wasn't.

If he's right, i'm 1000% more right. The park procedure covers this and about 30 billion other things. Give me a break.
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Old 09-13-09, 04:14 PM   #12
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That's quite the assumption to make given the symptoms.

OP:
I just rode a New 10 speed 3700 miles across the USA.
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Old 09-13-09, 04:57 PM   #13
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Thanks for your replies and time guys, here's the status quo:
All shifting is very normal and smooth, no problems whatsoever except that when I'm on higher rear gears, ie: the more I approach the smallest rear sprokets the more I hear a metallic noise while pedalling. I'm pretty sure it's the chain rubbing on the FD cage.
Thankyou for your patience considering I'm new at this.
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Old 09-13-09, 05:24 PM   #14
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It will most likely be a little tweaking with the barrel adjuster for the FD. Easy job.
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Old 09-13-09, 06:31 PM   #15
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Well here's what my shifter and barrel adjuster looks like.

I tried to rotate it but it only seemed to rotate in one direction and it has plastic teeth... I'm not sure if it's suppose to rotate. It didn't seem to rectify the problem. Is there a special way to do it?
Thanks again for your time.
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Old 09-13-09, 07:25 PM   #16
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Does it matter which of the front chainrings you are using? Are you using more than one?
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Old 09-13-09, 07:30 PM   #17
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I mostly use the second and third (front). The noise is most audible on second (front) and 5-6-7 rear.
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Old 09-13-09, 07:49 PM   #18
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I mostly use the second and third (front). The noise is most audible on second (front) and 5-6-7 rear.
If I understand correctly, you are using the middle, and large chainrings? And the noise is louder when on the middle ring? It does seem that the cable has slacked off some. Turn the barrel, the plastic "teeth" as if you were unscrewing it. You should see an inner sleeve start to come out. If you carefully note where the dérailleur is in relation to the chain, you should see it start to move outboard. Note, this can only give you comparatively small adjustment. If a couple of full turns haven't helped significantly, go to the link the others gave you and do a full adjustment procedure.

Dérailleur setup and adjustment is a common task on a bicycle that gets significant usage, it also needs to be done more often with cheaper components, it is a good skill to learn.
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Old 09-14-09, 02:15 PM   #19
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Yes you're right, the noise is louder when I'm on the middle front ring and the smallest rear ones.
I rotated the barrel adjuster as you instructed and I noticed the cage moving outward. I still have to ride the bike to test, cos I live in the city and I cannot ride often.
I'm building a work stand for my bike and will test as soon as I finish.
Thanks again for all your inputs.
I'll let you know if my issue is fixed.
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Old 09-14-09, 02:29 PM   #20
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Also check to see if the chain is rubbing on something else. As you get onto the smaller sprockets, the chain gets closer to the frame. This is a long shot, but there might be a cable end or some other thing that the chain contacts.
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Old 09-14-09, 02:49 PM   #21
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Hmmm... Dropped the chain to the inside. Maybe a bent FD Cage? Happens to me everytime I screw up and down shift under heavy load. Chain locks for a moment, then drops and the FD cage ends up bent.
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Old 09-14-09, 07:17 PM   #22
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Thanks for the replies.
The chain is not rubbing on the frame nor anything else but the cage.
I don't think the cage is bent, I'll take a pic and post it for you to see.
Thanks guys.
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Old 09-14-09, 07:35 PM   #23
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I am going tto go out on a limb here and say, the reason you are getting rub on the f derailer is because you are cross chaining. you need to move up to the big ring in front and one of the larger cogs in back. one
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Old 09-14-09, 08:51 PM   #24
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Chains rubbing on the front-derailleur cage can often be attributed to cross-chaining. Riding in gear combinations that cause too much deflection to the chain, such as large to large and small to small:

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Old 09-14-09, 08:51 PM   #25
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I am going tto go out on a limb here and say, the reason you are getting rub on the f derailer is because you are cross chaining. you need to move up to the big ring in front and one of the larger cogs in back. one
Ummm... No. That would result in cross chaining.
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