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Discussion Starter · #1 · (Edited)
This is probably an easy one but I am such a newb.
My bike is shifting OK but in the middle front chainring my chain rubs on the inside of the front derailleur just enough to make some noise and feel a little rough.
I just put a SRAM PC68 on it. Never noticed it before the chain change. After I realized what it was I redid the front derailleur (cable tension, limit screws, etc.) and it seems fine but for the rubbing in the middle chainring.
I think the PC68 is a slightly thicker than the chain that came on the bike. The original says KMC Z NARROW on it.
Figured you guys probably know what I've done wrong here and know simple fix.

EDIT: Sorry looks like I posted to the wrong forum. Is there a way I (or a mod) can delete this thread and I'll ask in the right place?
 

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I had that problem with an XT front derailleur. The derailleur cage needs to be as low to the outer chainring as specified - I think it's 1 or 2 mm. The cage is shaped where the upper part has more room than the lower part. Just having the derailleur slightly too high on the frame will cause the annoying rubbing.
 

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Discussion Starter · #3 ·
Thanks, I'll check out the height.
It only does it on the middle front ring though, not at all on the inner or outer chainring. Would that be a symptom of the derailleur being a little too high?
 

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Discussion Starter · #5 ·
Here's the specs on my bike, this is all I know, except I switched the awful twist shifters for Shimano EF50's and put a better saddle on it. Says stock chainrings are 28/38/48t This is Diamondback's details:

http://www.diamondback.com/bikes/mtn-hardtail/outlook-08/

I got the new chain now that I have over 60 miles on the bike and the original chain that came on the bike had a couple places that were twisted, so I got the PC68 to put on the bike and replaced the twisted links on the original with power links and thought I would carry that for a spare. After that is when I noticed the rubbing and noise. As I posted in my edit, I asked this in the Drivetrain forum also, as I figured this was not the right place after I thought about it. More info here:
http://forums.mtbr.com/showthread.php?t=427806
 

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I actually only had the problem with the middle ring also. It happened while on the middle ring and largest cog. The strange part about my problem was that I could trim the front derailleur cage to rub even more and the noise almost completely stopped. It wasn't completely fixed until I lowered my derailleur just right above the outer chainring.
 

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I fixed this same problem on my wifes Mongoose a couple days ago. That thing was a wreck but it's ready to shred some trails now. I made sure the front rings were lined up with the deraileur and the proper height (2-3mm). After I did that I adjusted the low and high screws until I could get through all the gears with no rubbing or sounds. I really didn't know what the hell I was doing I just tinkered with it until I could tell what it was doing and finally I got it all right and I am very proud of myself for "tuning" my first bike.
 
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