Bicycle Mechanics - 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.

Cables alway stretch on new bikes and you have to adjust them.

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.

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.

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.

I will.
Thanks for your help.
I'll let you know how it turns out :)

Do the full procedure. Do not skip steps.


+2 :thumb:

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?

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.

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?

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.

That's quite the assumption to make given the symptoms.

OP:
I just rode a New 10 speed 3700 miles across the USA.

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.

It will most likely be a little tweaking with the barrel adjuster for the FD. Easy job.

Well here's what my shifter and barrel adjuster looks like.
http://www.freeimagehosting.net/uploads/74e65af7fb.jpg
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.

Does it matter which of the front chainrings you are using? Are you using more than one?

I mostly use the second and third (front). The noise is most audible on second (front) and 5-6-7 rear.

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.

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.

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.

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.

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.

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

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:

http://i424.photobucket.com/albums/pp323/nagognog/cross-chainingissues.gif

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.

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:

http://i424.photobucket.com/albums/pp323/nagognog/cross-chainingissues.gif

He has already stated the noise is worse when in the Middle ring.

Covering all the bases for future readers using the Search-function.

Even in the middle-ring, I've seen problems with deflection as well.

Covering all the bases for future readers using the Search-function.

Even in the middle-ring, I've seen problems with deflection as well.

Fair enough, do think OP's problem is the cable has stretched.

I know it is. I suggest that people can negate this problem simply by installing a barrel-adjuster somewhere in the cable-line between the shifter and FD. Aside from those 3-position toy-adjusters that come with the shifters. By using these anytime the cable is changed (yearly is best) - the 'stretch' can easily be dialed-out.

Example of a Barrel-Adjuster in the FD line:


http://i424.photobucket.com/albums/pp323/nagognog/IMG_0538.jpg

Continuing to have to re-pull the cable at the pinch-bolt is both maddening, as well as being bad for the cable. These make it simple as all get-out. They can be used over & over for years:

http://www.biketoolsetc.com/index.cgi?id=180244260661&c=Cable-Housing&sc=Barrel-Adjusters

It could be that the counter shaft sprocket is worn as you say, or possibly it's worth checking the wheel alignment. Also put some more lube on the chain to see if it helps.

I just thought to mention that the adjustment you set often tightens up when you torque the axle nut up. Make sure it's still got the required tension and hasn't gone taut.



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I still have to test and check if the barrel adjuster trick made any difference. But since you guys are talking about cross-chaining, as I said, the bike only has about 150km and I always avoid the following gear combinations: 1(front)+ 5-6-7(rear) and 3(front)+ 1-2-3(rear) which in my understanding lead to cross-chaining. Please correct me if I'm wrong.
Dannydesilvia, the bike is still new, so I don't think anything could've been worn yet. How to I check the wheel alignment?
Thankyou all for your valuable inputs.

I checked today and there is still chain noise... It's like touching something and not rubbing. One thing I notice is that I hear the sound when I hit a bump or a small pothole, does this mean that my chain has more slack than it should?
I think this would result in the noise I'm hearing, am I right? How can I check this?
One more thing, when I hold the bike in my hand and bounce it a bit on the ground, I see the rear derailer pulley bounce up and down with the shock, should it be this loose?
Thanks guys for all your time.

Get a camera and proceed as follows:

Shift the derailleurs so you are in the Small/Small gear combination. I know this will cause cross-chaining, but the Bike-Gods will forgive you. Now take a photo showing the rear-derailleur (RD) side-on. I'm looking to see the position the RD is in with this combo.

Now do likewise after shifting to the Large/Large combination.

With these pictures we can deduce if the chain is too long, too short, or just right. Please make sure the wheel is properly mounted in the rear-dropouts beforehand.

Thanks Panthers for replying.
Would these photos do? I believe the chain should be just right length-wise, but I don't know if it's tight the way it should be.
Thanks again.
http://www.freeimagehosting.net/uploads/63832ce720.jpg
http://www.freeimagehosting.net/uploads/832f22e8aa.jpg

Thanks for the fast posting. The chain appears to be the optimal length for your set-up. But my Lordy! What's the number of cogs on your cassette? 13 - 40T? That's huge. And I'm not at all surprised it's making noises. That chain has a very tough job to do.

I'll wager this much: If you had a smaller cassette back there, the noise-problem would very likely be reduced. Please do post the sizes of both your cassette and your chainrings. It looks like you are probably right on the absolute maximum specs for your derailleurs.

Wow! And thanks again.

Thankyou for your reply :)
Well it's a stock Trek 3700 mod2009, no modifications at all.
The cassette is a Shimano TZ31 13-34, 7 speed Megarange, rear derailer Shimano Acera.
Front derailer is Shimano C051 and the Chainwheel is a 28/38/48.
The first couple of rides were noise free lol, today I went for a 20-mile ride, the shifting is smooth and pretty normal except for that noise while pedalling...
Should the rear derailer pulley be so easy to move up and down? It bounces on every bump and I hear a clunk on big bumps...

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.
There aren't 30 billion things on a bike.

Okay. Back to square one: No noise previously? Now a 20 mile ride and noise develops. This indicates nothing as much as indicating 'cable-stretch.'

So here we are again. In that you only have the stock barrel-adjuster that came with the brake-levers, your only recourse is to release the pinch-bolt on your front-derailleur (FD) and pull it taut - not so tight that you could shoot arrows with it - taut so there is discernible resistance to being moved. Then the pinch-bolt needs to be tightened down again to 48 - 60 inch-pounds (i.p.) of torque. A beam-type torque-wrench that measures from 0 - 60 i.p. is the tool you want.

This should make the FD run as silent as it did before. If it needs more than this by going out again from silent to noise: Reinstall the FD from scratch following directions previously given. And install a 'REAL' barrel-adjuster into the cable-line in the process. And use a new gear-cable. You should get it working perfectly - until this settles (stretches) and you need to pull the cable taut again. After one manual re-tensioning of the cable - to the pinch-bolt at 60 i.p. - IF it goes out again, use your new barrel-adjuster to make any correction in the cable-tension.

Whew!!

Can we see the chainline from the rear please. Middle ring, middle of the cogset. The less tension on the chain, the bigger the chain slap noise when you hit bumps. This is normal. We've already verified correct chain length. Nothing more you can do about this.

TheCROW, you are trimming the FD position as you shift across the rear-cluster?

Okay. Back to square one: No noise previously? Now a 20 mile ride and noise develops. This indicates nothing as much as indicating 'cable-stretch.'

So here we are again. In that you only have the stock barrel-adjuster that came with the brake-levers, your only recourse is to release the pinch-bolt on your front-derailleur (FD) and pull it taut - not so tight that you could shoot arrows with it - taut so there is discernible resistance to being moved. Then the pinch-bolt needs to be tightened down again to 48 - 60 inch-pounds (i.p.) of torque. A beam-type torque-wrench that measures from 0 - 60 i.p. is the tool you want.

This should make the FD run as silent as it did before. If it needs more than this by going out again from silent to noise: Reinstall the FD from scratch following directions previously given. And install a 'REAL' barrel-adjuster into the cable-line in the process. And use a new gear-cable. You should get it working perfectly - until this settles (stretches) and you need to pull the cable taut again. After one manual re-tensioning of the cable - to the pinch-bolt at 60 i.p. - IF it goes out again, use your new barrel-adjuster to make any correction in the cable-tension.

Whew!!

I'm really grateful for your taking the time :)
I will try this if I can find such a wrench, if not I will find myself compelled to go to my LBS.



Can we see the chainline from the rear please. Middle ring, middle of the cogset. The less tension on the chain, the bigger the chain slap noise when you hit bumps. This is normal. We've already verified correct chain length. Nothing more you can do about this.

Will this pic do?
http://www.freeimagehosting.net/uploads/73ee44a261.jpg


TheCROW, you are trimming the FD position as you shift across the rear-cluster?

Danno, sorry but I'm not sure I understand your question, I'm new to bike mechanics and terms :)
Thanks.

I think I win. That derailer looks bent to me.

The FD? or you mean it's cage?
Maybe because I tried to adjust the angle... Could this be it?

The rear of the cage may be rotated outwards too much in an attempt to ward off rubbing on the outside. I'll post some pictures on what "trimming" means. Basically adjusting the position of the RD my small amounts as you shift the rear to prevent rubbing. You move the FD a tiny amount, like 2-3mm. Enough to avoid the rubbing, but not enough to shift up into the big-ring.

The FD? or you mean it's cage?
Maybe because I tried to adjust the angle... Could this be it?

Semantics...

From Sheldon Brown:

"Angle of the front derailer is judged by looking down on the cage from above. Modern front derailers have very subtly shaped cages, so it is not always easy to tell when the ideal adjustment has been made. In general, the centerline of the cage should be parallel to the centerline of the frame. Rotating the derailer so that the back of the cage is farther out will sometimes improve shifting to the small ring of a triple by preventing overshifting, but may cause increased need for trimming on the larger rings. It may also cause the crank to strike the cage."

http://www.sheldonbrown.com/derailer-adjustment.html

Yours looks like the back is "way" out compared to the front, but as Sheldon states, it is hard to tell given the complex geometry.

you bent your derailluer or it got pulled out to one side or the other when your chain got caught

what was the verdict?

Trimming is one of those things that seems intuitive to me, having grown up learning bikes in the days before anything was "indexed", so that was my first thought.

probably a long shot, but if the FD isn't bent/twisted a bit, could there be a slight bend in a tooth of the center chainring?