Ghost shifting

[grenes]

Does anyone no the solution for ghost shifting? My local bike shop cannot fine tune my rear derallier for the trails. PLease help!
Thanks, Grenes:D

[jimilton80401]

grenes: It's important to know a few things about your situation:
What type of bike, drivetrain, how old, what have you done so far to fix the problem, etc. There are many variables involved in your dilemma.
For example, I have a friend whose bike suffered from ghostshifting (which I assume is a shift that takes place without you actuating a shift lever). We discovered that the derailleur hanger on her bike was too flexible and as the frame was made of steel, that the dropout needed replacing. What was happening was that the force of shifting was flexing the rear derailleur and the bike would over and undershift and sometimes, shift by itself in demanding situations. Due to the nature of the frame material, the whole rear triangle had to be replaced and repainted. The manufacturer and shop were able to work things out so the cost to my friend was reasonable.
It should be noted that this isn't a problem that always occurs with steel frames. My friend was a hard rider and had had many spills and had snapped several rear deralleurs on sticks and rocks, all of which contributed to the steel eventually fatguing beyond it's limits. She used a Smimano rear der. with a Sachs twist shifter. I remember the set up for that system to have been very fussy.

[a2psyklnut]

Hard to tell w/o touching and feeling!

One of the easiest things to do would be to make sure your cables are clean and well lubed. A little dirt or grit can cause the cables to hang up and could create problems.

I've had a similar problem to one of my bikes and finally tracked the problem down to a Neoprene (Lizard Skins) type chainstay protector interferring with the cable.

Another place to look would be the cassette. Make sure the retaining ring is tight. If there is play in the cassette, it'll move around and cause some freaky shifts. (Usually at the most inopportune time!). If you're running 7-speed on a 8 or 9 speed, make sure you're using the proper spacing.

What else? Make sure all your cable ferrules are in place and straight where the cable housings are attached to the frame/shifters/derailleurs. Had one ferrule at the shifter split and cause some mis-shifts through part of the gear range. Took forever to find that one!

Blah, Blah, check derailleur hanger alignment. A bent one will cause good shifting in the smaller cogs and misalignment in the bigger cogs and could cause the problems.

...etc, etc, etc.

L8R

[grenes]

Thanks for the great advice. When I took a closer look@ my cassette I discovered a small vine. When I removed it the mysterious shifting stopped. Thanks again, keep em spinning! Grenes