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Rear mech ghost shift.(7 posts)

Rear mech ghost shift.MichaelM
Sep 3, 2003 8:09 AM
I'm running a full 105 9 speed groupset, and as I set off and gain speed, changing up as I go the gears are fine. The shifting itself is spot on, the chain doesnt jump, but:

If I'm higher than about 5 or 6 and want to change down, I often - though not always have a 'ghost shift' first, as if the STI is taking up some slack. After this 1 ghost shift everything is fine, I can change down to my lowest gear or I can change up to my biggest gear - it's spot on untill I want to change down, then I have this ghost shift again, or maybe not - just sometimes, but frequently.

Does anyone else experience anything like this ? Have any ideas of what could be wrong?

Also it only happens on the road, if it's on a stand it seems ok.


need a new chain?? -nmfiltersweep
Sep 3, 2003 8:40 AM
re: Rear mech ghost shift.gtx
Sep 3, 2003 9:21 AM
I'm not sure what you mean by "change down" but the first things to check would be cable tension. If that's not it clean and lube you cables. If the cables and housing are old they may need to be replaced. Other things to check include cassette or chain wear and rear hanger alignment.
re: Rear mech ghost shift.MichaelM
Sep 3, 2003 11:51 AM
Change down - into a lower gear (larger sprocket).

I've ruled out cable tension, if it was too slack, the chain would be falling onto a smaller sprocket, if it was too tight, the chain would be trying to move onto a larger sprocket.

Also it only happens on the first attempt when changing gear involves a change of direction.
re: Rear mech ghost shift.gtx
Sep 3, 2003 12:42 PM
it's often hard to diagnose these over the net. Sometimes it's a fine line with cable tension, especially with these 9 and 10 speed systems. I guess it could also be an issue with your shifter. Try cleaning and lubing (light lube like Triflow) your cables and inspecting your housing for damage, kinks, etc., if that doesn't work, try the other things I mentioned. Unless it is a faulty shifter, the rest of this stuff is a very easy process of elimination.
B-screw is your answer.niteschaos
Sep 4, 2003 4:14 PM
Having mastered cable tension and it still shifts on you without asking permission first? Then you need to screw in the b-screw. Took my bike to 3 shops and they couldn't fix it. Then I remember that the b-screw was for these situations.
Clean and lube the nylon bracket under BB make sure no groove NM10speedfiend
Sep 6, 2003 1:27 AM