XT rear derailleur lateral play & ghost shifting

I

imago

Likes Bikes
Hey all,

I'm finding that I get a bit of ghost shifting when riding on singletrack over the past few months, mainly if I come out of a rocky section and go to accelerate again-the chain will skip back into gear on the cassette.

I've replaced the following parts over the past couple of months as they've worn out, hoping it would help solve the issue:
-Cables
-Cassette (XT)
-Jockey wheels
-Chain (XTR)

The only original parts are the rear derailleur (XT M772) and hanger, with about 5000km on them. I've visually checked the hanger against my spare, and it looks straight. The lower pivot has some lateral play, and I can move the cage at the lower jockey wheel about 5mm side to side. I've checked the Park Tools website and the Zinn book...but they don't specify a limit for play, I guess it depends on the model.

So....

1. Is it normal to jump out of gear on rocky track sections? Does this sound more like a cable adjustment issue than a derailleur problem?

2. How much lateral play is normal for the XT derailleur?

Thanks!
 
S

sedifus

Likes Dirt
1. While it may be normal for the gear to jump out it isn't supposed to. Cable tension may be the issue, maybe have it checked by a mechanic or a knowledgeable friend.

2. Almost no play should be Mohicans on a new derailleur. I'd say your pivots are worn. Can you borrow a friend's one or something and try it out with the rest of the system?
 
0

0psi

Eats Squid
Dually or hardtail?

If it's a dually I'm guessing a section of outer cable housing may be too short and as your suspension cycles it's effectively pulling on cable.
 
I

imago

Likes Bikes
It's a hardtail, I've had it checked by a mechanic recently, which was when the new cable was installed, unless maybe it has stretched since it was installed?

I've had a play with some new ones in the bike shop, and they all seemed to have some lateral movement. Mine does feel a bit looser though.
 
Mywifesirrational

Mywifesirrational

I however am very normal. Trust me.
I've had the same problem, with the exact same deraileur (from brand new), on my AM bike. Tried pretty much everything I could think to fix it to no avail.

Is it a long cage by chance? my only remedy was changing to a medium cage with a clutch mechanism, I have no idea exactly why this solved it - new deraileur? short cage? clutch?

I broke a few chains due ghost shifting under heavy load and it really p&^%$d me off, so I unhappily spent the money and now am at peace with the world.
 
S

sedifus

Likes Dirt
imago said:
It's a hardtail, I've had it checked by a mechanic recently, which was when the new cable was installed, unless maybe it has stretched since it was installed.
Click to expand...
It could have most definitely stretched. As a mechanic I find 6 weeks for an average Joe rider is checkup time. This equates to maybe 20 km, if that, so maybe this is your problem.

Find a YouTube video and have a quick play yourself, although it could end up worse than it is now you shouldn't be able to break anything.
 
Coaster

Coaster

Likes Bikes and Dirt
Did you replace the cable outers? You haven't mentioned them above. If you didn't the cable may be catching in the out. I had the exact same thing and it was as simple as replacing them to fix.

Cheers,

Coast
 
M

mumbleman

Likes Dirt
How old are your chainrings I have had this with a worn middle chain ring. Did not do it in big or small so I replaced the middle.
I also agree with the cable outers if you havent changed them.
 
I

imago

Likes Bikes
Cable outers are old, but I have lubricated them recently...might try new ones soon.

Just adjusted the cable tension too, so will see how that goes.

What's the consensus on a new derailleur...would it be worth giving a go?
 
redbruce

redbruce

Eats Squid
imago said:
Cable outers are old, but I have lubricated them recently...might try new ones soon.

Just adjusted the cable tension too, so will see how that goes.

What's the consensus on a new derailleur...would it be worth giving a go?
Click to expand...
Cable outer is cheaper and should be done anyway if you are going to put a new derailleur on.
 
F

frensham

Likes Dirt
imago said:
Cable outers are old, but I have lubricated them recently...might try new ones soon.

Just adjusted the cable tension too, so will see how that goes.

What's the consensus on a new derailleur...would it be worth giving a go?
Click to expand...
The old cable outers will now have a groove in them from the original cable. This will cause the new cable to drag in the groove and will not be good for crisp shifting and is probably the cause for you ghost shifting. On another note, have you had a really good look at your rear triangle? There could be a crack in one of the stays - have had experience with this. Bottom line, do you have a mate with a spare derailleur lying around his shed? - swap 'em over and see what happens. Alternatively, you can pick up a basic Deore rear for less than $30 online (in fact I just purchased a 9sp XT for $40).
 
S

StanzaRallyMan

Likes Bikes
+1 to chaning the outer housing. Its so cheap, that the moment any of my bikes start to feel sluggish when it comes to shifting, both the inner and outer housing are changed and shifting is restored to pristine levels.
 
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