Shift cable rubs against FD on smallest chainring
07-25-15, 08:34 AM
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Shift cable rubs against FD on smallest chainring
Hi. I'm working on my '92 Bridgestone MB-4. Specifically changing the grip shifts I installed in '98 to thumb type shifters. I wish I would have taken more detailed, "before," shots of the cable routing.
I removed the old housing and cables and installed jagwire. The FD cable routes under the bottom bracket and up to the FD anchor bolt. At least, I'm pretty sure that's how its supposed to route. The thing is when I shift to the smallest chainring, the FD seems to get in its own way -- and this is causing me grief in adjusting the tension. Will you please examine these pictures and let me know if I have this right? The derailleurs are original Shimano Deore LX.
The pictures in order are: under the bb, the FD & anchor bolt on the largest chainring, the FD rubbing when on the smallest chainring, the FD itself, and the new shifter.
I removed the old housing and cables and installed jagwire. The FD cable routes under the bottom bracket and up to the FD anchor bolt. At least, I'm pretty sure that's how its supposed to route. The thing is when I shift to the smallest chainring, the FD seems to get in its own way -- and this is causing me grief in adjusting the tension. Will you please examine these pictures and let me know if I have this right? The derailleurs are original Shimano Deore LX.
The pictures in order are: under the bb, the FD & anchor bolt on the largest chainring, the FD rubbing when on the smallest chainring, the FD itself, and the new shifter.
07-25-15, 09:26 AM
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Looks the the BB cable guide might be adjustable left-right. Can you move it a bit, which will move the cable inwards a bit ?
Also, can you route the cable over the other side of the clamp, closer to the frame ? I'm not sure from here which is the "correct" route on that FD.
Also, can you route the cable over the other side of the clamp, closer to the frame ? I'm not sure from here which is the "correct" route on that FD.
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07-25-15, 09:33 AM
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True, provided the cable in not interfering with shifting to the small ring.
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07-25-15, 09:38 AM
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Picture number 2...appears the cable is not attached correctly. Should go over the nub, not under.
07-25-15, 09:50 AM
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Also moving the guide to the left would help. I believe that that's a two position guide, with 2 holes or a slot in the plastic and you move it by reversing the metal fastening plate.
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Last edited by FBinNY; 07-25-15 at 09:59 AM.
07-25-15, 12:04 PM
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This is the key. It might not solve everything, but should improve things somewhat. The wire is supposed to go to the far side (toward he frame) of the bottom nub and bend to the right under the pinch bolt. (remove the bolt and washer and you should see a groove in the arm confirming this) That will move the wire inboard a bit, but more importantly correct the travel ratio and improve trim in the 3 positions, by effectively lengthening the arm.
Also moving the guide to the left would help. I believe that that's a two position guide, with 2 holes or a slot in the plastic and you move it by reversing the metal fastening plate.
Also moving the guide to the left would help. I believe that that's a two position guide, with 2 holes or a slot in the plastic and you move it by reversing the metal fastening plate.
After an hour (sigh) of tweaking, unfortunately I still couldn't get it to shift to my satisfaction level. I'm at about 80% of the 21 gears pedaling without friction, but seeking better. I decided to remove the part and give it a cleaning, then some oil.
07-25-15, 02:11 PM
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Sweet success! Thanks again for the help!
A link to a front derailleur video. And two pictures: 1.) what a 23 year old frame looks like without its FD, 2.) over the nib and through the groove.
A link to a front derailleur video. And two pictures: 1.) what a 23 year old frame looks like without its FD, 2.) over the nib and through the groove.
07-25-15, 02:18 PM
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It's so easy ------- once you know how.
BTW- I see you had to back off the cable so there a crushed area on the working side. The cable bends back and forth there as the arm swings, and so is prone to work hardening and breakage there. The fraying speeds up that process, so cable life will be shorter.
Nothing urgent, you have plenty of time, but at some time when it's convenient, buy yourself a gear inner wire so you're ready when the time comes, which may be 6 months or 6 years or something in between.
BTW- I see you had to back off the cable so there a crushed area on the working side. The cable bends back and forth there as the arm swings, and so is prone to work hardening and breakage there. The fraying speeds up that process, so cable life will be shorter.
Nothing urgent, you have plenty of time, but at some time when it's convenient, buy yourself a gear inner wire so you're ready when the time comes, which may be 6 months or 6 years or something in between.
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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.
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WARNING, I'm from New York. Thin skinned people should maintain safe distance.
FB
Chain-L site
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.
