Front derailleur issues
12-09-10, 05:59 PM
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Front derailleur issues
Hi all,
I've got a triple chainring - Shimano 105. I've somehow lost the ability to shift from the middle to the bottom chainring - the deraileur moves without a problem, but the chain doesn't move with it. When I'm in the middle chainring the cable is tight, but when I try to shift down to the lowest ring, the cable goes slack as the derailleur moves, but the chain stays on the middle ring.
Shifting up is fine, as is shifting down from the top to middle. No problems with the rear either.
I've tried using the barrel adjustor to loosen the cable tension, but it doesn't seem to be making a difference.
Any ideas?
I've got a triple chainring - Shimano 105. I've somehow lost the ability to shift from the middle to the bottom chainring - the deraileur moves without a problem, but the chain doesn't move with it. When I'm in the middle chainring the cable is tight, but when I try to shift down to the lowest ring, the cable goes slack as the derailleur moves, but the chain stays on the middle ring.
Shifting up is fine, as is shifting down from the top to middle. No problems with the rear either.
I've tried using the barrel adjustor to loosen the cable tension, but it doesn't seem to be making a difference.
Any ideas?
12-09-10, 06:24 PM
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Where does the cable slack occur? If it is slack at the derailleur then something at the derailleur is keeping it from moving, maybe the low limit screw is set incorrectly. If the slack occurs between the housing stop of the down tube and the bottom bracket then the cable must be hung up on the cable guide below the bottom bracket. Check to see if the cable is routed properly.
Instructions for setting up and adjusting derailleurs can be found at www.parktool.com.
Instructions for setting up and adjusting derailleurs can be found at www.parktool.com.
12-09-10, 06:35 PM
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tart by making sure that nothing is obstructing the FD's movement. I've seen all sorts of stuff get stuck in them. Assuming it's clear, then check that the inner limit isn't too tight. Try backing it off 1 full turn and see if things change. Suggestion --adjust the inner limit with the FD cable tensioned a bit to lift it off a bit. If adjusting the limit doesn't change anything restore it to it's original position, and go back and check for something restricting movement.
If moving the inner limit screw made a difference, fine tune it for optimum trim on the inner ring, while still getting good crisp shifting.
In case you're wondering why it changed, it might be because as your chain aged it become more flexible and now require more aggressive acting from the FD.
If moving the inner limit screw made a difference, fine tune it for optimum trim on the inner ring, while still getting good crisp shifting.
In case you're wondering why it changed, it might be because as your chain aged it become more flexible and now require more aggressive acting from the FD.
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An ounce of diagnosis is worth a pound of cure.
Just because I'm tired of arguing, doesn't mean you're right.
“One accurate measurement is worth a thousand expert opinions” - Adm Grace Murray Hopper - USN
WARNING, I'm from New York. Thin skinned people should maintain safe distance.
12-09-10, 09:15 PM
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Don't bother adjusting anything.
The only reason that derailleur would stop shifting to the small ring is because
1) Contaminated cable + housing
2) Derailleur rotated to a different position, e.g getting hit by something
3) Extremely worn chain
Use your brain to figure out which one it is.
The only reason that derailleur would stop shifting to the small ring is because
1) Contaminated cable + housing
2) Derailleur rotated to a different position, e.g getting hit by something
3) Extremely worn chain
Use your brain to figure out which one it is.
