Help - Front Derailleur

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2006-06-21 9:22 PM

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Subject: Help - Front Derailleur
I need help - Just brought home my new cervelo dual and the damn chain rubs against the front derailler cage in the big chain ring ... I know the adjustment must be easy to do - I just need to now how to make the adjustment . FYI the front derailleur is brazed on. Thanks in advance.

2006-06-21 9:27 PM
in reply to: #462332

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Champion
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Fairport, NY
Subject: RE: Help - Front Derailleur

If a brand new Dual has even the slightest setup issue, it should be brought right back to the shop. Any bike that you spend that kind of money on should be perfect when you walk out the door with it.

Having said that, it is new, and things take time to settle in and will move a bit. Have the LBS adjust it and give the whole bike a once over.

Question: how long did they spend fitting the bike to you?

2006-06-21 9:36 PM
in reply to: #462332

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Subject: RE: Help - Front Derailleur
The bike shop I purchased it is 2 hours away and I have a race this weekend. They took alot of time to fit me and everything seemed okay. I believe things may have moved when I placed in the back seat to take it home. I was nervous to place it in the trunk rack do to my accident last week where someone rear-ended me and put an end to my new felt tribike. I just hope maybe I can make the adjustment myself with a little help.
2006-06-21 10:20 PM
in reply to: #462332

Master
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Shreveport, LA
Subject: RE: Help - Front Derailleur
This is a pretty easy fix.

If the chain rub is happening while you have "chain cross" (big chainring in front and lowest gear (biggest cog) in the back), then not much you can do.

If it is not then just trace the cable from the front derailleur to the cable stop and adjust the tension with the barrel adjuster either way until the chain rub stops. If this doesn't fix it, try adjusting the barrel adjuster on the deraill

Don't mess with the limit screws.

2006-06-21 10:24 PM
in reply to: #462332

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Subject: RE: Help - Front Derailleur
It does rub in the big ring in front and large one in back - There is nothing I can do ?
2006-06-21 10:29 PM
in reply to: #462384

Master
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Shreveport, LA
Subject: RE: Help - Front Derailleur
toby 71 - 2006-06-21 10:24 PM

It does rub in the big ring in front and large one in back - There is nothing I can do ?


Nope. This is normal for all bikes.

If you are in the large ring in the front and the big cog in the back, you should shift down to the small chain ring and find a cog where you can keep your cadence where you want it. There is some overlap between the small ring and higher gears (smaller cogs) and the big ring and lower gears (larger cogs).

You should be able to find a speed that fits you without chain rub.

2006-06-22 8:38 AM
in reply to: #462332

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Fairport, NY
Subject: RE: Help - Front Derailleur

what mnewton said.

You want to avoid "chain cross" because it will cause the drive train to wear unevenly reducing the life of your chain, chainring and cassette.

2006-06-22 8:43 AM
in reply to: #462382

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Subject: RE: Help - Front Derailleur
mnewton - 2006-06-21 11:20 PM

If it is not then just trace the cable from the front derailleur to the cable stop and adjust the tension with the barrel adjuster either way until the chain rub stops. If this doesn't fix it, try adjusting the barrel adjuster on the deraill

Don't mess with the limit screws.



It's amazing when I go to BT to ask a question and the top question is exactly it. Well, almost exactly. My problem is when I'm in small chain ring and the two highest (small cogs) gears. How do I fix that? Just like you described above?

Thanks!!
2006-06-22 8:49 AM
in reply to: #462594

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Subject: RE: Help - Front Derailleur

paTRIck - 2006-06-22 8:43 AM
mnewton - 2006-06-21 11:20 PM If it is not then just trace the cable from the front derailleur to the cable stop and adjust the tension with the barrel adjuster either way until the chain rub stops. If this doesn't fix it, try adjusting the barrel adjuster on the deraill Don't mess with the limit screws.
It's amazing when I go to BT to ask a question and the top question is exactly it. Well, almost exactly. My problem is when I'm in small chain ring and the two highest (small cogs) gears. How do I fix that? Just like you described above? Thanks!!

Similar to what mnewton says, don't do this either. If you're on the small chainrings, stay off the small cogs, if you're on the big, stay off the big. There are alternative gears that will suit you well without putting your drive train under duress.

2006-06-22 8:52 AM
in reply to: #462594

Master
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Shreveport, LA
Subject: RE: Help - Front Derailleur
paTRIck - 2006-06-22 8:43 AM

It's amazing when I go to BT to ask a question and the top question is exactly it. Well, almost exactly. My problem is when I'm in small chain ring and the two highest (small cogs) gears. How do I fix that? Just like you described above?

Thanks!!


I installed new cables a few weeks ago and got some chain rub the past few days in the middle (I ride a triple) ring and the three highest gears. Last night I adjusted the tension of the cable and now all is well.

I would not go the "chain cross" with the small ring and small cog as said above. Shift up to the big cog and shift down to a lower gear (larger cog).





Edited by mnewton 2006-06-22 8:53 AM
2006-06-22 8:55 AM
in reply to: #462332

Master
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Shreveport, LA
Subject: RE: Help - Front Derailleur
Check this out to help you understand how the gears "overlap"

http://sheldonbrown.com/gears/

2006-06-22 8:55 AM
in reply to: #462594

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Subject: RE: Help - Front Derailleur

paTRIck - 2006-06-22 9:43 AM
mnewton - 2006-06-21 11:20 PM If it is not then just trace the cable from the front derailleur to the cable stop and adjust the tension with the barrel adjuster either way until the chain rub stops. If this doesn't fix it, try adjusting the barrel adjuster on the deraill Don't mess with the limit screws.
It's amazing when I go to BT to ask a question and the top question is exactly it. Well, almost exactly. My problem is when I'm in small chain ring and the two highest (small cogs) gears. How do I fix that? Just like you described above? Thanks!!

That would also be chain cross and is actually worse than the big chainring to low gears cross (at least accoring to Sheldon Brown). If you're in the small chainring and need to upshift, you should shift to the big chainring before getting the the smallest cogs on the cassette.

Like mnewton said, there is some overlap in the gearing available with multiple chainrings, so if you have 2 chainrings and there are 9 cogs on your cassette you don't have 18 available gears on your bike. You actually have 15 or 16.

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