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Old 01-18-10, 11:51 AM   #1
zeo_max
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Is chain rub on the front deraileur wall normal ?

I have a MTB with a 3 x 8 drivetrain setup and when placed in the tallest gear combo (biggest cog up front, smallest cog back) the chain rubs against the front deraileur's wall, or side, whatever you call it. Is this normal ?
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Old 01-18-10, 11:59 AM   #2
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no. adjust it with the help of parktool or sheldons site
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Old 01-18-10, 11:59 AM   #3
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I have a MTB with a 3 x 8 drivetrain setup and when placed in the tallest gear combo (biggest cog up front, smallest cog back) the chain rubs against the front deraileur's wall, or side, whatever you call it. Is this normal ?
No, this is not normal at the gear combo you described. You need to do a front derailleur adjustment. Go to Park Tool's website or Bicycletutor.com to see how to adjust the front derailleur.
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Old 01-18-10, 12:01 PM   #4
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A properly adjusted front derailleur should not let the chain rub on the inside of the cage (that's what it's called) plate in the smallest cog and largest chainring. An adjustment to the cable tension should correct it. If the cage won't move any further outboard, the high limit screw can be loosened slightly.
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Old 01-18-10, 06:39 PM   #5
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I'm using this video: http://bicycletutor.com/adjust-front-derailer/

And I wanna know something. At 2:45, he talks about using the shifter barrel adjuster to eliminate chain rub on the sides of the cage. Is this the only adjustment I have to do out of all others shown in the video ? My gears shift just dandy, the only problem is the chain rub, and I don't wanna mess up my gear system by trying to fix something that didn't need to be fixed.

Also, if the chain is rubbing on the left side of the cage (when looking at it from the position of sitting on the bike) do I have to turn the shifter barrel adjuster Clockwise or CounterClockwise ?
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Old 01-19-10, 12:24 AM   #6
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After properly adjusting the cable to your front-derailleur (FD), after riding a bit - the cable will stretch and the cage of the FD may well start rubbing. Now you can loosen the cable anchor-bolt and pull the cable tight again and secure the bolt with 48 - 60 ip. OR you can have installed an inline barrel-adjuster and give it a small tweak to re-adjust the cable without even getting off the bike. Or slowing down.

Here are the barrel-adjusters I recommend:

http://www.biketoolsetc.com/index.cg...rrel-Adjusters

Here's one ready to roll:


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Old 01-19-10, 12:49 AM   #7
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There are two adjustments needed to manage the outermost position of the FD cage. The outer (H) limit screw which, as its name implies, determines how far the cage can move. And the cable tension, or trim adjustment which actually controls the position with respect to the lever position. First test the limit position by actuating the FD directly with your hand, or by pulling the wire away from the downtube to see if it will move farther out. If not, back off the limit screw and test again until you've solved the rubbing problem. Next use the adjusting barrel to increase the cable and move the cage out to the desired position.

When you've adjusted the trim based on the outer/outer combination test FD shifting and trim for the other chainrings. You might have to readjust the trim for the best all around performance rather than the one combination only. Sometimes a bit of compromise is needed.
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Old 01-19-10, 12:57 AM   #8
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Originally Posted by zeo_max View Post
I'm using this video: http://bicycletutor.com/adjust-front-derailer/

And I wanna know something. At 2:45, he talks about using the shifter barrel adjuster to eliminate chain rub on the sides of the cage. Is this the only adjustment I have to do out of all others shown in the video ? My gears shift just dandy, the only problem is the chain rub, and I don't wanna mess up my gear system by trying to fix something that didn't need to be fixed.

Also, if the chain is rubbing on the left side of the cage (when looking at it from the position of sitting on the bike) do I have to turn the shifter barrel adjuster Clockwise or CounterClockwise ?
Clockwise.
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Old 01-19-10, 08:18 AM   #9
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Clockwise.
Wrong.

If the chain is rubbing the left side of the cage, it needs a limit screw adjustment.
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Old 01-19-10, 11:15 AM   #10
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Wrong.

If the chain is rubbing the left side of the cage, it needs a limit screw adjustment.
Ever tire of being ignorant?

Decrease tension on the cable moves the cage to the "left" - which is clockwise on the barrel adjuster. If you actually viewed the video, he's talking about adjusting the cage in the *middle* ring, which means limit screw have NO EFFECT.

Take the garbage you post and put it elsewhere and learn to read.
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