Chain touching front derailleur
08-03-11, 02:46 PM
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Chain touching front derailleur
Little background. I have a trek pdx that came with a c101 front derailleur, long story short the c101 wasn't doing it for me so I bought a Deore XT M770 to replace it. The bike is 8x3 speed with an LX rear derailleur.
I've installed it and it works a lot better then the c101, however if I am in the 1st gear in front that chain touches the derailleur when the rear is in 1st and 4th. In first it touches the inner part of the cage and in 4th it touches the outer part.
It just barely touches and adjusting the lower limit screw doesn't seem to do anything (broken? How much should it move, I can take it from completely tightened to all the way out and not notice a difference). Only way I've been able to avoid it is by rotating the derailleur but then it will either hit one or the other, can't avoid it on both.
Any thoughts/recommendations? Maybe my chain is just too wide since it is an 8 speed and the derailleur is "meant" for 9 speed? I don't know much about chains, it has hg50 on it, are there smaller chains for an 8 speed cassette?
Thanks
I've installed it and it works a lot better then the c101, however if I am in the 1st gear in front that chain touches the derailleur when the rear is in 1st and 4th. In first it touches the inner part of the cage and in 4th it touches the outer part.
It just barely touches and adjusting the lower limit screw doesn't seem to do anything (broken? How much should it move, I can take it from completely tightened to all the way out and not notice a difference). Only way I've been able to avoid it is by rotating the derailleur but then it will either hit one or the other, can't avoid it on both.
Any thoughts/recommendations? Maybe my chain is just too wide since it is an 8 speed and the derailleur is "meant" for 9 speed? I don't know much about chains, it has hg50 on it, are there smaller chains for an 8 speed cassette?
Thanks
08-03-11, 02:57 PM
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I suspect you have too much friction on the shift cable. How long has it been since you replaced the shift cables and cable housings?
Try flushing out the shifter(s) with WD40. Use the straw to shoot it right into the shifters. This will loosen up hardened grease and other crud that collects with time.
You can try fixing the problem by reducing cable tension with the barrel adjuster, but that may be a temporary fix if the cable housings or shifters are full of crud.
Check in at www.parktool.com for derailleur adjustment instructions.
Try flushing out the shifter(s) with WD40. Use the straw to shoot it right into the shifters. This will loosen up hardened grease and other crud that collects with time.
You can try fixing the problem by reducing cable tension with the barrel adjuster, but that may be a temporary fix if the cable housings or shifters are full of crud.
Check in at www.parktool.com for derailleur adjustment instructions.
08-03-11, 03:04 PM
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The shifter cables and housing are new from the start of summer, late May/early June. The cable is pretty tight, the new derailleur had to be placed a little higher then the old one for clearance. I'll try that out.
Any other suggestions are greatly appreciated. I'm quite new to this.
Any other suggestions are greatly appreciated. I'm quite new to this.
08-03-11, 05:47 PM
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SPiercey: Trying to adjust the low limit screw with the cable taut will not work. Try following these instructions: https://www.parktool.com/blog/repair-...ur-adjustments. Start at the beginning and follow them step-by-step without skipping any steps. you may still have a bit of derailleur rubbing when cross-chained; just don't do it.
