Ok, I know there are loads of threads on this and the only solution seems to be to file the damn thing down but surly that can't be the case!

My top jockey wheel is about 12mm away from the largest sprocket and it shifts like a total dog! The b-tension thing is as far out as it will go so there seems to be nothing I can do other that take some rather nasty tools to an expensive rear mech….surely not???

Isn't 12mm about right?

Had no problems with my Shadow

12mm is loads – should be about half of that

Is it mounted properly on the hanger?

Make sure the mech isn't rotating clockwise when you tighten the mech onto the hanger. Thread needs to be greased and hold it in place for the final tweak. Look at mech from the rear, make sure there's no gap between the mech's stop tab and the hanger. If all is correct, file down the mech hanger, not the mech.

Is the length of cable outer leading into the mech the correct length?

Buy cheap, buy twice. Should have got an acera mate.

I had no problems setting mine up.

Yeah it's fitted properly, the stop is butted right up against the tab on the dropout. Shimano say it should be about 6mm, I'm double that!

It shifts so bad it's unreal, it's indexed right and it's not too bad going down but going up it's all over the place, shifting under any sort of pressure is not ever worth thinking about!

maybe go to your LBS explain the problem.

Whilst at the LBS get them to put your frame in jig if they have one, check the hanger is still straight. Was it working OK with your previous mech? If that died a spectacular death did it damage the hanger at all?

If it was fitted properly then it would work correctly, go see your LBS.

2 for cable loop being too short and restricting the mech's forward movement, come across it regularly on new bikes(and some built by qualified mechanics who should really have picked this up).Worth checking before a journey to the LBS.

It's a warranty replaced frame so it's a brand new mech hanger. I've had the cables off so no restriction on that count. The only think stopping in going forward is the tab on the mech that hits the dropout.

There isn't a LBS round here that I would trust to even know what they're doing. Evans cycles trying to bash my XTR cranks with a hammer instead of using the proper tool to get them off still rings in the back of my head!

You will find that some frames put the mech further away than others, if you're sure there's nothing else wrong then file back the tab on the dropout as suggested above.

Don't file anything, you don't need to do that!

I'd say bent hanger, they frequently are on new bikes, we always straighten them when building.

+1 for bent hanger. Spent ages sorting my wife's brand new Spesh. Whinged to the supplier and they sent out a new hanger and mech next day by which time I had straightened and sorted so I had some spares.

For it to be the mech hanger it would have to be bent backwards to move the jockey wheel away from the cassette which I would have thought nigh on impossible. I'll check it though, I had the same problem on the previous frame which kind of points me away from the dropout.

I'll try and get some photos

Why? You're assuming (I suggest incorrectly) the the problems are related to the distance from the jockey wheel to the cassette.

I'd move it a bit closer than 12mm FWIW.

As I said earlier you probably just need more/longer cable outer to the mech 😉

If the outer is too short it doesn't shift correctly beleive me I had the exact same problem with my XTR shadow.

But if you want to start bending your frame or filing your mech down first, carry on

I think the point is he can't.. 🙂

Hi Paul, if you need to borrow a mech hanger alignment tool I've got one I can drop round for you.

+1 for the outer length … my SLX did this until I read the
installation instructions – DOH !

I can move the mech freely with the cable attached there is no resistance preventing it getting close to the jockey wheel. It is resting on the stops.

The reason I think (I'm 99% certain) that the distance is causing the shift problems is that the gap is huge Shimano recommends no more than 6mm…I'm at least 6mm greater than that. The flex in the chain alone would cause an inaccurate shift

Geoff might be worth a try just to rule it out as a problem. You can have a look on Thursday and give an opinion.

Ok, here's some photos to try and illustrate the problem…

The gap..flippen miles away…

pushed right against the stop

Cable ok