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Old 03-27-09, 11:57 PM   #1
jch3n
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fd chain rub

so i'm pretty much done with my new build, except for one small issue. there seems to be a chain clearance issue with the front derailleur in the small/large chainring and cog combo.



i'm using an '09 campy veloce fd (which is supposedly universal for both compact and standard road cranksets) and a race face cadence standard road crankset with the x-type external bottom bracket. i'm fairly certain this is the maximum inside position for the fd. on top of that i have both crankset chain line spacers on the drive side and i haven't tightened the crankbolt to the maximum. the instructions for the crankset state that the crankbolt should reach a hard stop, which i have yet to experience even while trying to max out the bolt, but if i tighten it any tighter than it is now the chain will rub the inside of the fd. what gives?

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Old 03-28-09, 12:48 AM   #2
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Small to small is known as cross-chaining, where the chain is as bent as it can be given the bike it's on. The other cross-chaining combo is large to large. And yes - these may rub the FD. But you shouldn't be riding in small/small or large/large either. It's bad for the whole drivetrain.

Shimano nowadays includes a chart with their FD's to show you what combinations are most likely to rub. I enclose a copy below:

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Old 03-28-09, 12:57 AM   #3
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wups!! i meant small chainring and largest cog. i definitely know what cross-chaining is.

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Old 03-28-09, 12:58 AM   #4
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if you are in your small-small, and the chain is actually hitting the inner plate of the FD, you need to go readjust your FD low limit and cable tension.
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Old 03-28-09, 12:59 AM   #5
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go unscrew the low limit of the FD, take a brush and clean out any dirt.
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Old 03-28-09, 01:08 AM   #6
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go unscrew the low limit of the FD, take a brush and clean out any dirt.
uhh, it's brand new. there is no dirt...
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Old 03-28-09, 07:49 AM   #7
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Is the FD cage parallel to the chainrings? The photo makes it look like maybe it's not.
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Old 03-28-09, 08:24 AM   #8
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Is the FD cage parallel to the chainrings? The photo makes it look like maybe it's not.
+1

It looks like you might have to rotate the FD a little clockwise (in respect to your picture) to bring the back of it a little closer to the frame. Not too much or you might get rubbing on the Big/Small combo.
It can be a little tricky.
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Old 03-28-09, 10:08 AM   #9
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Looks parallel to me. 1. Unbolt your cable from the derailer. 2. Adjust the inner limit. 3. Reattach cable, adjust pull if necessary.
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Old 03-28-09, 10:30 AM   #10
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Here's a couple of links that should help:

http://bicycletutor.com/adjust-front-derailer/

and...

http://www.parktool.com/repair/readhowto.asp?id=75
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Old 03-28-09, 12:39 PM   #11
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Looks parallel to me. 1. Unbolt your cable from the derailer. 2. Adjust the inner limit. 3. Reattach cable, adjust pull if necessary.
thanks, this did the trick. guess it was some weird cable tension issue. could've sworn i had the fd adjusted correctly before i installed the cable though...apparently not.
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