Rear Derailer Help

[jugheaddave]

Hi

 

Got a strange problem maybe you can help.

 

When I am in the last two (smalles gears) at the back and middle or big ring in front, I get a little bit of "ghost shifting" on the last two(smallest gears). This only seems to happen when I am pedaling hard over fairly bumpy terrain.

 

Now before you say, cables chain cassteet ect, this has all been recently replaced (as part of my anual service). I though this issue would be resolved with all the new gear, but it still prevales.

 

I was wondering if perhads my derailer spring (07 XT) is getting a little stretched, hence not holding the gear correctly?????

 

Any ideas????

Maybe B screw adjustment??

 

[Dirtbreath]

Had a similar problem. My RD was a short cage which I changed to a long. Also check the wear on your jockey wheels.

[jugheaddave]

Jockey wheels are fairly new. I got some of them CNC alu ones

[Dirtbreath]

Your hanger straight? And a new one wont guarantee it being straight.

 

Not familiar with the KCNC jockey wheels. They the same no. of teeth?

 

Your chain length OK?

 

[paulvs]

could just be a sticky cable - try rock 'en roll cable magic

[Wyatt Earp]

What bike ?

[Johan Bornman]

Ghost shifting as you describe, over hard terrain or when pedalling hard usually indicate that frame flex causes relative changes in cable length. It usually happens on road bikes where the lower cable guide is exposed and the cable doesn't run in an outer. A bit of Energade dripping down from the bottle gunks up the guide and you get delayed shifting as the cable actuation is retarded by the goo.

 

You don't say whether your ghost shifting is temporary or permanent. In other words, does it shift up and down or just one way and then stay there? Does it cause the erratic shifting directly after you've shifted gears or simply out of the blue?

 

Also, describe the cable routing to us.

 

To help you and others eliminate this problem, remember that ghost shifting has nothing to do with worn parts. The problem is almost always because of the cable.

 

[jugheaddave]

Hi Guys

 

Thanks for all the feed back.

 

The bike is a 2007 Giant Anthem.

 

 

https://www.bikehub.co.za/forum_posts.asp?TID=40716

 

 The ghost shifting is only in the smallest two gears. It shifts up and down in those small gears ie permanent.

If I change up(slightly bigger on the rear) everything is fine. Like I mentioned the cables are brand new XTR.

 

I will check the hanger, and also try some different jockey wheels.

What about chain length, should I go slightly shorter?

 

[Serendipity]

I had a similar problem with my Giant - also an XT RD. What worked for my was fitting an X9 RD . I also know of people who changed the guide for the cable to the RD by running the outer all the way to the last cable guide on the rear triangle. Apparently you just open the little holes your cable runs through to fit the outer as well. You then have less chance of dirt and grime causing friction.

 

 

 

Otherwise - a new set of XTR cables always help.

[jugheaddave]

like i said just installed new xtr cables

[TYGA]

You get little gizmos which allow you to run a continuous cable casing without drilling out the cable lugs on your frame.

[Piernas Flacas]

Ghost shifting is normally caused by the spookes.

 

 

(ok, outta here now)

 

[Master216]

Had the same prob, replaced cables and housing to enclosed, made a huge difference, also the time before that it was my RD, the top nuckle had seized stiff, had it soak in Q20 for a couple of days and then serviced, now havent had that proble again....touch wood!!

[Heliboy]

Have a look at your frame, also had the same problem turned out to be a crack in the chain stay. Once replaced problem gone

[Johan Bornman]

You say you have installed new cables. Somewhere there is still friction. It is usually caused by a combination of frame flex and friction.

 

 

[Climate]

You mention that shifting up (to the slightly bigger sprocket) seems to work okay ... which means that once you've applied pressure to the cable, things stay aligned. So I gotta agree with Johan, that there has to be friction keeping the cable from releasing completely (and will be magnified when you get down to the smaller sprockets, because your jockey spring may not be as active when you get to that end of the range). You gotta have a look at the cable guide that passes under your BB - it could be the culprit, due to old juice that typically leaks from a juice bottle in a bottle-cage.