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Old 04-19-05, 01:16 PM   #1
kid charlemagne
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Newby: Chain rattles/buzzes when in big ring and 3 largest cogs

Hi,

I'm pretty new to cycling and just recently got my bike back from the LBS after its first tuneup. I have a 2004 Lemond Reno with a double chainring and a tiagra front derailleur and a 105 rear. I noticed that when I'm in the big ring and any of the 3 largest rear cogs, I get a faint buzzing/rattling from my chain, that is more noticeable during a portion of my crank's revolution, so it sounds like a cyclical zzzz...zzzz....zzzz whenever I pedal. I think it's my chain rubbing against my front derailleur, but I could be wrong. This only happens when I'm in the big ring and is more noticeable when I'm in the largest cog (I know, I shouldn't be in a big/big gear combo, but I did it just for troubleshooting purposes) and less noticeable as I go to the 2nd and third largest cog in the rear.

What are your thoughts to troubleshoot and fix this? I keep reading about 'trim' adjustments. Could a 'trim' adjustment be what I need? If so, what is this trim adjustment and how do I do it?

I don't want to go back to the LBS if it's a quick fix I could do at home.

thanks in advance!
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Old 04-19-05, 01:18 PM   #2
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You shouldn't be riding in that combination.

Dr., It huts when I do this.

Enjoy
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Old 04-19-05, 01:23 PM   #3
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Thanks. I know I shouldn't be riding in big ring/biggest cog, but what about the others. I should be able to use the other low gears with the big ring, right? Otherwise my so called 18 speeds are really only 10 or so.
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Old 04-19-05, 01:29 PM   #4
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Quote:
Originally Posted by kid charlemagne
Thanks. I know I shouldn't be riding in big ring/biggest cog, but what about the others. I should be able to use the other low gears with the big ring, right? Otherwise my so called 18 speeds are really only 10 or so.
Correct, you don't get as many useable gear combinations as you think you should .

Basically, you can use the gears up to the point where the chain starts hitting the front derailer (the source of the buzzing sound). If you had friction shifters or some kind of trimmer for your front shifter, you would be able to move the FD slightly inward and use another gear or two. Possibly you can adjust your front derailer limit screw inward a bit, and get another useable gear, but if you overdo it you won't be able to shift onto the big ring at all!

But it's still not a very good idea. Running the chain at a steep angle decreases the efficiency of the drivetrain and causes chain and sprockets to wear out quickly.
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Old 04-19-05, 02:33 PM   #5
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Originally Posted by moxfyre
Correct, you don't get as many useable gear combinations as you think you should .
Makes sense, but sheesh - what a gyp
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Old 04-19-05, 03:35 PM   #6
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You can usually get to the next largest without rub if you really tweak your adjustment in. This is OK according to Shimano. Most people go a little more conservative and stay out of the top two.

You should be able to easily use the third one. You probably just need a little front der adjustment.

I use the next to big and have no wear problems. 4000 miles and my chain measures out fine with a Park chain checker.
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Old 04-19-05, 07:55 PM   #7
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Well, don't do that!!
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Old 04-20-05, 10:14 AM   #8
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Patient: Doc. It hurts every time I lilft my arm like this.
Doctor: Don't lift your arm like that. My consultation fee is $50. Please pay the cashier on the way out.


--hmmm very helpful.
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Old 04-20-05, 01:33 PM   #9
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You probably can't be on the smallest ring + 3 smallest cogs. EDIT: in a double, you can. The first trim position allows you to use the larger cogs, the 2nd trim position allows you to use the smaller cogs.
Or largest ring + 3 largest cogs.

There are 2 positions that you can trim for your middle ring for the front derailleur, inner and outer.
For the 5 largest cogs, use the inner position. For the 4 smallest cogs, use the outer position.

Last edited by slvoid; 04-23-05 at 10:03 PM.
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Old 04-21-05, 05:29 PM   #10
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He has a double, not a triple.

Either take it back to the LBS or learn to adjust the FD yourself. On my Versailles (which I think has the same geometry) which is the double 105/Ultegra combination, I can use all 9 cogs with the big ring and all but the smallest with the small ring. Now I don't really use the biggest two cogs with the big ring because I can't imagine the chain likes it, but with the FD properly adjusted, it doesn't rub, either. It did take me some time adjusting it to get it to work right.

Bruce
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Old 04-21-05, 08:51 PM   #11
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Quote:
Originally Posted by Bruce Lowekamp
He has a double, not a triple.

Either take it back to the LBS or learn to adjust the FD yourself. On my Versailles (which I think has the same geometry) which is the double 105/Ultegra combination, I can use all 9 cogs with the big ring and all but the smallest with the small ring. Now I don't really use the biggest two cogs with the big ring because I can't imagine the chain likes it, but with the FD properly adjusted, it doesn't rub, either. It did take me some time adjusting it to get it to work right.

Bruce
I have a full ultegra double groupo, the same rules apply. The front derailleur has 2 trim positions.
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Old 04-21-05, 09:24 PM   #12
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As slvoid says, "trim" your front derailer (which is a bit of a trick to master in STI---or RapidFire, come to think of it!).

If that fails, you may need to make some minor adjustments in the system, usually by "tweaking" the cable at the adjuster(s).

You should, in a "double", be able to use all but the largest rear cog with the 'big" ring; the opposite is true with the "small" ring. However, it is more "efficient" to shift in front once you are much past the "middle cog" in the rear in either direction: the chain "running" angle is less extreme and reduces wear on the entire system.
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Old 04-23-05, 04:15 PM   #13
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Thanks for your responses!

How do I 'trim' my front derailleur using the STI shifters?

Thanks!
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Old 04-23-05, 05:36 PM   #14
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Quote:
Originally Posted by kid charlemagne
Hi,

I'm pretty new to cycling and just recently got my bike back from the LBS after its first tuneup. I have a 2004 Lemond Reno with a double chainring and a tiagra front derailleur and a 105 rear. I noticed that when I'm in the big ring and any of the 3 largest rear cogs, I get a faint buzzing/rattling from my chain, that is more noticeable during a portion of my crank's revolution, so it sounds like a cyclical zzzz...zzzz....zzzz whenever I pedal. I think it's my chain rubbing against my front derailleur, but I could be wrong. This only happens when I'm in the big ring and is more noticeable when I'm in the largest cog (I know, I shouldn't be in a big/big gear combo, but I did it just for troubleshooting purposes) and less noticeable as I go to the 2nd and third largest cog in the rear.

What are your thoughts to troubleshoot and fix this? I keep reading about 'trim' adjustments. Could a 'trim' adjustment be what I need? If so, what is this trim adjustment and how do I do it?

I don't want to go back to the LBS if it's a quick fix I could do at home.

thanks in advance!
Why don't you try using the trim function in the shifter?
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Old 04-23-05, 05:39 PM   #15
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Quote:
Originally Posted by Avalanche325

You should be able to easily use the third one. You probably just need a little front der adjustment.
It's just back from the shop(Yeah I know nose pickers,but sometimes they get it right)..Haven't you heard of the trim function in the front shifter?

Last edited by sydney; 04-23-05 at 06:01 PM.
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Old 04-23-05, 05:41 PM   #16
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Quote:
Originally Posted by moxfyre
If you had friction shifters or some kind of trimmer for your front shifter, you would be able to move the FD slightly inward and use another gear or two. Possibly you can adjust your front derailer limit screw inward a bit, and get another useable gear, but if you overdo it you won't be able to shift onto the big ring at all!
HE has trim in the front shifter ! Assuming the derailer is adjusted and set up right to start with.
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Old 04-23-05, 05:44 PM   #17
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Quote:
Originally Posted by slvoid
You probably can't be on the smallest ring + 3 smallest cogs.
Or largest ring + 3 largest cogs.

There are 2 positions that you can trim for your middle ring for the front derailleur, inner and outer.
For the 5 largest cogs, use the inner position. For the 4 smallest cogs, use the outer position.
Yes he can...He's got a double!!
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Old 04-23-05, 06:00 PM   #18
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Quote:
Originally Posted by kid charlemagne
Thanks for your responses!

How do I 'trim' my front derailleur using the STI shifters?

Thanks!
This assumes it's setup right for a double and the shifter starts in the granny ring position for your small ring and uses the middle ring position for your big ring. It aslo assumes the shop hasn't set the hi limit so tight that the trim is unusable,and that the shifter was in the full granny position when the cable was attached.It's easy to screw up the trim function with improper setup. When you are in the big ring, and the chain starts rubbing the derailer when in the bigger cogs, a light touch of the small lever toward the right will move the derailer cage slightly to the left. A light touch means not enough to cause a shift to the small ring.When in the small ring and shifting toward the smaller cogs, a light touch(partial shift) on the brake lever to move it slightly right will move the derailer cage slightly to the right. Again a light touch being considrble less than it takes to shift to the big ring.
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Old 04-23-05, 10:02 PM   #19
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Quote:
Originally Posted by sydney
Yes he can...He's got a double!!
Oh yea, true that.
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Old 04-23-05, 10:07 PM   #20
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Quote:
Originally Posted by kid charlemagne
Thanks for your responses!
How do I 'trim' my front derailleur using the STI shifters?
Thanks!
Your left shifter (which shifts the front shifter), the large lever shifts to the larger ring, the smaller shifter snaps it back to the smaller ring.
Put your gearing into the small ring. Then gently start pushing on the large lever until you feel it "click". Notice it'll move the front derailleur out slightly but not all the way over the large ring. This position allows your chain to "bend" more towards the smallest cogs on the back w/o rubbing the derailleur.
So on the large lever, a "half click" brings you from the inner to outer position for the small ring. A full click swings the derailleur out to the large ring. If you click the small lever, it brings it all the way to the inner position for the small ring.
It takes some getting used to, like finding neutral (especially from 2nd gear) on a motorcycle.
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Old 04-25-05, 02:21 PM   #21
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There's good advice in the responses. But, there are other adjustments besides the movement caused by your front DR shifter. The height (or clearance) between the lower edge of the outer derailleur plate and the large chainring and the relative alignment (the degree of parallel) between the outer DR plate and the large chainring when viewed from above looking down, are two adjustments that should always be checked before changing the outer or inner stop limits. I suggest making the clearance and alignment adjustments with the chain removed and the DR cable detached. First make sure the DR is aligned to your chainring. Loosen the DR clamping screw until you can rotate the DR on the seat tube. By viewing the chainring and DR from above rotate the DR until the outer plate and oputer chainring are aligned. The clearance on both my 105 DR and my Dura Ace DR are set to about between .5 and 1mm. Be sure and rotate your crank slowly to make sure that even the highest chainring tooth maintains that small clearance to the the DR outer plate. Now I set the inner DR stop. That's the natural position for the front DR without a cable attached. The correct position is given as a specified gap between the inner DR plate and the smallest chainring. Use the inner stop limit screw to set this. Attach the cable and take up any slack before you tighten the allen screw that holds the cable. Shift the front DR to the outer chainring position. The correct outer position is a specified gap between the outer DR plate and the large chainring. Check either Park tool website or the maker of your derailleur for the correct gap specs. My experience with correctly adjusted and well maintained drive systems with a double chainring, is silent operation in all gear/chainring combinations. With tripples, I've never been able to get a silent drive train with the biggest/smallest combo. It always makes some noise. But of course there's good reason never to use the extreme gear/chainring combinations, as my other forum friends have already said.
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Old 05-20-05, 02:37 PM   #22
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- tks... my experience ("Start the Wayback Machine, Sherman," said Mr. Peabody) with a double was that yes, no trouble on any gearing combo... a triple (and i have the same components at the OP) appears to posit problems...

- which means that yes, indeed, there is room for innovation in the bicycle industry!

:-)
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