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Old 10-25-10, 04:35 PM   #1
Yemff
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Shimano 105 Sti left small shift lever hard to push

I just installed a set of 105 sti shifters (double, with new cables/housing/lube) and the left small shift lever is harder to push than any of the other levers on both the left and right side. The feeling when shifting is more like a push then a breaking loose, instead of more smooth transition. The large lever is working fine, but when shifting from the large chainring to the small it takes a fairly good amount of force to shift, at least compared to shifting in the rear. This only seems to happen when the shifter gets tension from the front derailler, as it did not do this when not hooked up. I'm new to road biking and have nothing to compare to, so my question is if this is normal? Thanks for the help
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Old 10-25-10, 05:22 PM   #2
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is the cable head seated in the socket ? did you start in the smallest( low) gear ? is the cable hanging up somewhere in side the housing or frame? is there dirt in the front dérailleur ? no this not normal . you said it work fine off the bike so it have to be something wrong when you set it up.
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Old 10-25-10, 07:03 PM   #3
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Possibly too much cable tension?
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Old 10-25-10, 07:11 PM   #4
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Possibly too much cable tension?
thats my guess
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Old 10-25-10, 09:03 PM   #5
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Could be a problem with cable routing on front derailleur... if the cable does not go over a little tab on top of the pinch bolt the effective lever arm will be shortened and require super high cable tension to operate; super high cable tension might be what you are fighting against to 'release' the internals to downshift on the front.

Also you might have the front derailleur set up so it is jammed up into the 'H' limit screw when in big ring, also causing high tension thatmust be overcome to release. To fix you must undo the cable and start from square 1 - set derailleur alignment (100% perfectly parallel with chainrings) and height (1 - 3 mm above big ring - no more).
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Old 10-26-10, 09:15 AM   #6
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Ok I have since tried and checked all of your suggestions. The cable is mounted correctly and so is the front derailler, as well as the limit screws set correctly. But as you all said it still seems like excess tension is coming from somewhere. When I got the frame and installed the derailler cables I did notice that the plastic cable guide under the bottom bracket doesnt seem to be long enough, and the cable rubs the frame where the cable exits the guide and goes up to the front derailler between the chain stays. Would this be enough to cause this extra tension? Thanks again
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Old 10-26-10, 09:44 AM   #7
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Also you might have the front derailleur set up so it is jammed up into the 'H' limit screw when in big ring, also causing high tension thatmust be overcome to release. To fix you must undo the cable and start from square 1 -
I'd revisit this, though the fix is simply to loosen the H limit screw about an eighth turn.
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Old 10-26-10, 10:02 AM   #8
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Yes I have, I even went to the extreme and loosened it considerably more, but the high tension still remains. But I guess I'll go over it a 3rd time
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Old 10-26-10, 12:00 PM   #9
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I think your shifter is working normally--just takes getting used to.
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Old 10-26-10, 12:45 PM   #10
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I think your shifter is working normally--just takes getting used to.
Yeah I dont see what could be wrong aside from the rubbing on the frame. Ive gone over everything many times and everything is adjusted fine. And when I just run the shifter with the cable disconnected, but pulling on the cable to put some tension on it, it still shifts pretty rough compared to the rear.

Last edited by Yemff; 10-27-10 at 09:32 AM.
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Old 10-26-10, 05:16 PM   #11
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I just installed a set of 105 sti shifters (double, with new cables/housing/lube) and the left small shift lever is harder to push than any of the other levers on both the left and right side.
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...when I just run the shifter with the cable disconnected, but pulling on the cable to put some tension on it, it still shifts pretty rough compared to the front.
??? The left lever is for the front. Is the installation backwards???
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Old 10-26-10, 06:36 PM   #12
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I did notice that the plastic cable guide under the bottom bracket doesnt seem to be long enough, and the cable rubs the frame where the cable exits the guide and goes up to the front derailler between the chain stays. Would this be enough to cause this extra tension? Thanks again
The guides I've seen have a short side and a long side. The short side is for the rear derailleur and the long side is for the front. The cable should not rub the frame. I'm wondering if the guide is mounted backwards.
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Old 10-27-10, 09:29 AM   #13
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??? The left lever is for the front. Is the installation backwards???
Sorry I meant rear

Last edited by Yemff; 10-27-10 at 09:36 AM.
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Old 10-27-10, 09:31 AM   #14
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No its not backwards but there is a considerable amount of weld between the chain stays, so the cable does rub a little
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