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Old 05-15-12, 05:54 PM   #1
Pricey Socks
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Need help troubleshooting my shifting mechanism problems

First off, I am very new to bicycle culture/maintenance, so please, go easy.

I just bought a bike (1974 Peugeot 10 speed according to craigslist add) for $100 so that I could have a road bike that was in working order, but had room to improve/upgrade/learn on. I have successfully replaced the brakes and adjusted them to my liking (go me), and now I am working on swapping out some friction shifters that are mounted on the downtube with some ones off my old junker that are mounted on the handlebar stem. Obviously cables from the old shifter mechanism were too short, so I salvaged the cables from the handlebar stem which seemed to be in better condition anyway. My issue right now is that while I can shift one way (towards the smaller gears, up, down, whichever direction that is, sorry), the tension isn't released when I want to shift the other way. The old shifter mechanisms worked, so I'm thinking maybe it's the cable? Also while researching I discovered that the housing for the shifters appear to be brake cable casing instead of shifter cable casing. I don't know how big of a difference that makes. Also, the casings don't seem to have barrel adjusters. I did, however, lubricate the cable with some 3-in-1 where the cable goes through the casing.

I can post pictures if necessary
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Old 05-15-12, 07:15 PM   #2
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Grease the cables. 3 in 1 is oil and won't stay on the cable. Check the ends of housing for burrs. And check the cable routing especially at transition points (e.g. coming out of the shifter, tucking down near the braze on down tube bosses, under the BB, etc. if that's the way your cables are routed. Lube the derailleur pivot points and pulleys as well.
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Old 05-16-12, 01:06 AM   #3
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Originally Posted by Pricey Socks View Post
My issue right now is that while I can shift one way (towards the smaller gears, up, down, whichever direction that is, sorry), the tension isn't released when I want to shift the other way.
The derailleurs shift to smaller gears when you release the tension. Shifting the other way happens by pulling the cable.

Unless you have an odd rear derailleur.
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Old 05-16-12, 09:58 AM   #4
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Grease the cables. 3 in 1 is oil and won't stay on the cable. Check the ends of housing for burrs. And check the cable routing especially at transition points (e.g. coming out of the shifter, tucking down near the braze on down tube bosses, under the BB, etc. if that's the way your cables are routed. Lube the derailleur pivot points and pulleys as well.
This .... something is binding the cable, so inspect it end to end.
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Old 05-16-12, 05:15 PM   #5
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Ok, so I just went to a LBS and got some new cable and cable housing to replace the old stuff, and now I'm having the opposite problem. I can still shift, but now once I take my finger off the lever, the tension isn't held and it shifts right back to the small gear. Could the new housing do this if it is too long? And if it is too long, can I cut it with regular wire cutters or would that pinch it shut?
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Old 05-16-12, 05:35 PM   #6
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You need to look at the shift system and think about how it works instead of doing hit-and-miss guessing. There is a solid cable connecting the deraillueur, which wants to spring away from the center of the bike (smaller/fewer teeth gears in the rear) to the lever, which either pulls the derailleur toward the center of the bike when you pull back on the lever or allows a spring in the derailleru to move it outward when you move the lever forward. If the derailleur moves "on it's own" it's because the lever is moving. Why would the lever NOT normally move? Because it's held in place by friction. Therefore the lever has tool little friction, not the cables. There is a wingnut or screw with a large flat slot that goes through the pivot of each lever. Tighten that enough that the lever no longer allows the derailleur to shift when you let go of the lever.

BTW, the downtube levers you replaced generally are much more efficient (take less travel, had less friction) than the stem shifters you installed. The extra cable housing creates more flex and friction and you exert a turning force on the handlebar when you shift.

p.s. Brakes have even stronger springs, so poorly lubricated cables may not be noticed, but be aware that they need lubrication as well - will work much easier. If the housings are lined (plastic inside) then it's best to use a light oil, rather than grease, especially on shift cables.

Last edited by cny-bikeman; 05-16-12 at 05:41 PM.
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Old 05-16-12, 05:57 PM   #7
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Most friction shifters hold the derailleur in place by... friction. So if your derailleur spring is pulling the cable and shifting to a smaller sprocket (larger gear), then look for some kind of adjustment on the shifter near the pivot point to tighten the friction. Might be a D-ring or might be a screwdriver slot.
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Old 05-16-12, 06:13 PM   #8
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Most friction shifters hold the derailleur in place by... friction. So if your derailleur spring is pulling the cable and shifting to a smaller sprocket (larger gear), then look for some kind of adjustment on the shifter near the pivot point to tighten the friction. Might be a D-ring or might be a screwdriver slot.
Made this for another thread, but you get the idea-



Tighten the bolt/screw/D-ring circled in this pic.
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