rear derailleur keeps jumping back
06-24-11 | 09:29 AM
#3
Senior Member
Joined: Apr 2009
Posts: 39,897
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From: New Rochelle, NY
Bikes: too many bikes from 1967 10s (5x2)Frejus to a Sumitomo Ti/Chorus aluminum 10s (10x2), plus one non-susp mtn bike I use as my commuter
If you mean it's shifting back to high gear (outward) on the spring after you shift, the remedy depends on whether you have index or friction shifting.
RD's are spring outward, and move inward when pulled by the cable. Keeping the position is always in the lever. With friction shifting (most downtube levers) there's a small friction clutch in the lever that can be adjusted by turning the mounting screw or wingnut.
Index levers use latching clicks to keep the position in each position. These are not adjustable, and usually not repairable either. One exception is Campagnolo where the latching springs are replaceable when they get weak.
For other index levers you can try a Hail Mary, hoping that the levers are simply gunked up and sticking. Douse the mechanism with WD-40 or your favorite solvent, work the levers back and forth, and let it dry overnight. If it now works, apply a light spray oil as a lube, and make a donation to your favorite charity for continued good Karma.
RD's are spring outward, and move inward when pulled by the cable. Keeping the position is always in the lever. With friction shifting (most downtube levers) there's a small friction clutch in the lever that can be adjusted by turning the mounting screw or wingnut.
Index levers use latching clicks to keep the position in each position. These are not adjustable, and usually not repairable either. One exception is Campagnolo where the latching springs are replaceable when they get weak.
For other index levers you can try a Hail Mary, hoping that the levers are simply gunked up and sticking. Douse the mechanism with WD-40 or your favorite solvent, work the levers back and forth, and let it dry overnight. If it now works, apply a light spray oil as a lube, and make a donation to your favorite charity for continued good Karma.
__________________
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.
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.
Last edited by FBinNY; 06-24-11 at 09:35 AM.
