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Old 04-09-11, 07:05 PM   #1
MKIV987
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Excessive shifter cable tension on 105 Front Derailleur

So my 105 FD won't shift into my big chainring. My shifts are small, in that I have to shift three times to reach the second ring and after that it feels like there's too much tension on the shifter cable to shift up. When I shift down, the FD *pops* back into the small ring like it's been under a lot of tension. I messed around with my limit screws to no avail. There was nothing I messed with before this happened that could have caused it, so where's this tension coming from? Any guesses? Thanks guys
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Old 04-09-11, 07:16 PM   #2
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Has nothing to do with the limit screws.
Go to www.parktool.com for instructions for dérailleur tension and limit adjustments. Most bikes have barrel adjusters for tension adjustments.
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Old 04-09-11, 07:41 PM   #3
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Originally Posted by MKIV987 View Post
So my 105 FD won't shift into my big chainring. My shifts are small, in that I have to shift three times to reach the second ring and after that it feels like there's too much tension on the shifter cable to shift up. When I shift down, the FD *pops* back into the small ring like it's been under a lot of tension. I messed around with my limit screws to no avail. There was nothing I messed with before this happened that could have caused it, so where's this tension coming from? Any guesses? Thanks guys
It sounds like you have the opposite problem. Not enough tension - it's taking three upshifts because you have a lot of cable to pull that isn't moving the FD. The 'tension' you feel is because your shifter can't shift any further, it's already gone through all it's clicks.

Shift down as far as the shifter will go, then feel the cable. Is there a lot of slack or is it tight?
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Old 04-11-11, 06:52 PM   #4
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The FD cable is pretty slack when in the smallest ring.
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Old 04-11-11, 08:41 PM   #5
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The FD cable is pretty slack when in the smallest ring.
Should be no slack. Should possibly need to have a slight amount of tension when on the smallest ring.
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Old 04-11-11, 08:47 PM   #6
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Right...you need to have your limit screws set prior to setting the tension in your cable. Once you have your lower and upper limits set, you can set and tighten the cable while the shifter/derailleur is in the small ring position. Once this is done, you can make the fine tuning adjustments to the cable via the barrel adjuster.
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Old 04-11-11, 09:40 PM   #7
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Sorry guys, I feel like a major dunce here, but I appreciate the help so far...

I've set my lower limit screw, but I'm unable to set my upper limit since I can't shift into the big ring. Once my derailleur is as far out as it can go (the middle ring) then I can adjust my upper limit screws, but it'll only move the derailleur towards the frame, not out to the big ring like I need. I tried tightening the cable while I was in the small ring but it really wouldn't get much tighter and it didn't seem to solve anything. Are the barrel adjusters where my problem is?
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Old 04-11-11, 09:51 PM   #8
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Your problem is the cable tension. Set the lower screw, then pull the cable tight and re-clamp it. I believe on your shifters it should be two clicks to get to the middle ring. If you aren't getting there in two clicks, you should tighten the cable until you do. Then go to the big ring and set the upper limit. Remember that on the barrel adjusters, lefty tightens the cable, righty loosens it.
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Old 04-11-11, 10:18 PM   #9
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My guess is you're misrouting the front derailleur inner wire.



The wire goes over the little tab before it gets pinched by the bolt. If you route it under, it pulls the wrong amount of cable with excessive tension.
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Old 04-13-11, 09:01 PM   #10
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Originally Posted by Nerull View Post
It sounds like you have the opposite problem. Not enough tension - it's taking three upshifts because you have a lot of cable to pull that isn't moving the FD. The 'tension' you feel is because your shifter can't shift any further, it's already gone through all it's clicks.
If this is 105-5600, it gets more complicated. Most 5600 front shifters are triples, so it sounds like you're ratcheting all the way through the middle position and using the third to get to the outer ring.

Shift all the way down, then tighten the cable just enough to get the chain up to the big ring consistently with one full push on the lever. There should be a little bit of cable slack when in the first (inner) position. After you've got that outer position on the first pull sussed, fine tune so you're not getting chain rub on your outer-outer combination. Then tighten down that limit screw so you don't shift past it. The cage should hit the limit screw at the same time it hits the end of the cable.

Fine tune for your big-ring trim position. If the cable pulls too tight against the limit screw, down shifts will be rough and the trim position might be impossible to hit. You should be able to hit it with a gentle click on the downshift paddle.

Too many riders were breaking their 5600 triples on doubles. The cable would stretch, so they'd shift into the third position, jamming the everything so tight against the limit screw that there was too much resistance in the downshift paddle. Then they'd force it and break the shifter. Shimano started making 5600 doubles but it was too little, too late for most people.

A lot of shop mechanics aren't even aware of this issue.
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Old 04-13-11, 09:27 PM   #11
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Curious thread - to the OP, i have a similar but inverse situation. My FD gets the chain out to the big ring just fine, but won't bring it back to the middle from the big, or the little from the middle.

I tried to set my inner limit and put the FD just shy (about .25 mm) from grounding out on the seat tube, and it still wouldn't move the chain to the inner ring . .. so I got to looking at the ring positions and I saw that my right (fixed) BB cup was all the way in - no more threads showing and the left (adjustable) had about 3-4 mm of threads showing on the left side . .. I ended up repositioning the BB along the lateral axis about 4 mm and BANG, I can shift down now . ..

maybe yours is too far to the right (drive) side?
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Old 05-05-12, 07:26 AM   #12
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[QUOTE=Al1943;12483668]Has nothing to do with the limit screws.
Go to www.parktool.com for instructions for dérailleur tension and limit adjustments. Most bikes have barrel adjusters for tension adjustments.

Likely not a problem setting tension. Sounds like cable is on wrong side of clamp bolt. If you clamp the cable on the wrong side the lever arm is changed by more than 50% the result is that you need an excessive amount of force (tension) to shift from small chainring to large furthermore upon downshifting the derailleur spring has a huge lever arm causing a rapid movement with the derailleur crashing into the lower limit with a loud thwack. Easy mistake to make and easy to fix. There should be a visible groove to show you which side is correct but you can also figure it out by looking at the hinging of the derailleur to make sure that you are on the side of the bolt to give the longer lever arm for the tension from the cable and hence the smaller amount of force from your shifter
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