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Old 06-12-03, 08:59 PM   #1
FOG
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Won't shift to inner chain ring

I just bought a used bike on e-bay and it won't shift to the inner chain ring on a triple. It is a '99 lemond BA with 105 STI's. It looks to me as though the front derailleur cable is too short. I tried adjusting the barrel nuts, and they either bottom out or just make it worse. I think I need a new, longer derailleur cable but it might be something to do with the shifter. Do all '99 105 shifters shift a front triple? Is there a way the innards of the shifter could have been damaged to make shifting to the inner ring impossible? The reason I am doubting the cable is the problem is it doesn't make sense that anyone would install a cable so short it wouldn't allow a shift to the inner chainring, and cables generally stretch,, not shrink, in service. On the other hand, maybe the guy who had it did something to screw it up.
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Old 06-12-03, 09:15 PM   #2
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The two small screws on top of the derailler are stops. So the chain doesn't go too far. The one which stops the chain from going in too far might be mis-adjusted. I think it's the outside screw.
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Old 06-12-03, 09:18 PM   #3
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Quote:
Originally posted by Dirtgrinder
The two small screws on top of the derailler are stops. So the chain doesn't go too far. The one which stops the chain from going in too far might be mis-adjusted. I think it's the outside screw.
there are H and L screws. This limit the movement of the derailer... Adjust it..

Did you by any chance replaced your BB? If you did, maybe its too short...
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Old 06-12-03, 10:20 PM   #4
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I bought the bike used- no idea what was replaced. heck, for all I know it is a two speed front derailleur
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Old 06-13-03, 02:48 PM   #5
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sounds like you have a replaced crankset, but I always thought that your particular bike came with a double ring setup?
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Old 06-13-03, 03:00 PM   #6
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Some other things to check.

When you attempt to shift to the inner chainring, is the cable loose or is it still taut?

If it still has tension, loosen the derailleur cable and see if it shifts to the inner chainring. If it does, remove all the slack in the cable and tighten it back up. You may have to set the L limit screw so the derailleur doesn't overshift to the inside. Make sure that you can shift into all of the chainrings.

If the cable is slack after trying to shift onto the inner chainring, then check the lower limit screw. Maybe the previous owner didn't use the inner ring and adjusted the limit screw accordingly.

I've used an old Dura-Ace fr. derailleur on my road bike (set up with Campy Triple) with no ill effect for 3-4 years.
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Old 06-13-03, 03:01 PM   #7
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The diagnosis is simple. If the cable is always under tension, even in low gear, then it is keeping the cage from swinging far enough inward to effect the 2->1 gear change. If the cable goes slightly slack, then the cage motion is probably being limited by the L adjustment screw, which needs to be backed out a bit. Another possibility is that the front derailleur is either bent or misaligned.

Step 1: Make sure the cage is parallel to the chainrings. With a bolt-on (rather than old-fashioned clamp-on) derailleur, you may need to replace the unit and/or straighten the frame's braze-on.
Step 2: Make sure you have a bit of cable slack in low gear. If the cable projects past the fixing bolt and nut, you can loosen the nut to cut yourself a bit of slack. (It sounds as though turning the adjusting barrel is lengthening your housing, and therefore effectively tightening your cable.)
Step 3: If the cage still does not swing far enough inward, try turning the L screw anti-clockwise. If this does not permit the cage to move farther inward, check the derailleur for damage, stiffness, or perhaps a weakened return spring.

Good luck. Let us know what you discover.
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Old 06-13-03, 08:12 PM   #8
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Quote:
Originally posted by John E
The diagnosis is simple. If the cable is always under tension, even in low gear, then it is keeping the cage from swinging far enough inward to effect the 2->1 gear change. If the cable goes slightly slack, then the cage motion is probably being limited by the L adjustment screw, which needs to be backed out a bit. Another possibility is that the front derailleur is either bent or misaligned.

Step 1: Make sure the cage is parallel to the chainrings. With a bolt-on (rather than old-fashioned clamp-on) derailleur, you may need to replace the unit and/or straighten the frame's braze-on.
Step 2: Make sure you have a bit of cable slack in low gear. If the cable projects past the fixing bolt and nut, you can loosen the nut to cut yourself a bit of slack. (It sounds as though turning the adjusting barrel is lengthening your housing, and therefore effectively tightening your cable.)
Step 3: If the cage still does not swing far enough inward, try turning the L screw anti-clockwise. If this does not permit the cage to move farther inward, check the derailleur for damage, stiffness, or perhaps a weakened return spring.

Good luck. Let us know what you discover.
After checking here to make sure I wasn't going into anything weird, and calling the seller to make sure he hadn't done something strange like hooking a trple chain ring up to a double FD, I figured out that all I needed to do was have more slack in the cable, just as in your suggestion 2. That did the trick all by itself. I wanted to scope it out here because I worry that I might overlook something simple, given that it is a system new to me. Thanks to all here for their help.
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