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Front derailleur adjustment- not enough cable pull?
#1
I probably have 10+ hours into trying to adjust my front derailleur. It's a a 1999 Trek 8500 (Deore LX front top-pull derailleur). I've watched the bicycletutor video, followed the Park Tool guide and the Shimano installation/adjustment directions repeatedly with no luck.

After positioning the derailleur and adjusting the lower limit screw for proper positioning in low gear, I can not get the front derailleur in high gear with out significant rubbing on the outside plate, even after fully loosening the upper limit screw. If I use my hand to put additional tension on the cable, I can get the derailleur to where it needs to be and there's no rubbing.

I've tried using the barrel adjuster to adjust cable tension. If I adjust it to the point that its not rubbing on the outer plate in high gear, then there is a huge amount of rubbing on the inner plate in low gear (even with the lower limit screw completely loosened).

In short, it seems that I'm not able to get enough travel between low and high gears using the shifters. It does not appear possible to adjust the shifter to change the amount of cable pull between gears.

Is this an issue with the shifter, the derailleur, the cable, or am I just failing at properly adjusting?
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#2
Be sure to put the crank at a 3 o'clock position, then pulling manually the derailleur, see if there's a 2 mm gap between cage and chainring...

Also be sure that your derailleur is parallel to your chainrings, if it's a bit misaligned, you'll have some rubbing for sure...,
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#3
(05-26-2012, 01:10 PM)bobtravers Wrote:  Be sure to put the crank at a 3 o'clock position, then pulling manually the derailleur, see if there's a 2 mm gap between cage and chainring...

Also be sure that your derailleur is parallel to your chainrings, if it's a bit misaligned, you'll have some rubbing for sure...,

Bob - thanks for the response...

I figured out what was going on.... in short I was an idiot.

I just got my bike work stand about a week ago... Instead of clamping to the seat post like everybody else in the free world does, I elected to clamp to the top tube. That was pinching down on the shift cable for the front derailleur and was preventing the shifter from pulling as much as it normally does.

I can't believe how much time I sank into that....! doh.
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#4
yeah, you only do it once.
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