Please tell me this will never work!

Can you add a photo of the inside of the chainstay?

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Mech looks to be completely wrong angle

I agree with Weeksy, that derailleur looks rotated too far clockwise to me. Is the little plastic wedge that sits against the B-screw in the right place?

https://si.shimano.com/en/dm/MARD001/Adjusting_the_end_adjust_bolt

If you're 'sure' it's not the hanger then I've found the Shimano 12s stuff to be very sensitive to the B-screw being set right

Sadly the angle of the mech is dictated by the mech hanger and yes plastic tab on the correct side. Anyway I just removed the mech, re installed it and torqued it up and I am getting more consistent shifting now so thanks for promoting me into the mech position! I also lubed the (new) cable to limit friction. The shifter feel doesn't seem right so I am blaming too much friction despite a brand new outer too... Will have a shake down on the trail. Thanks all.

Posted by: spannermonkey

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If you're 'sure' it's not the hanger then

... yr chain must be too long as I bet it fouls itself in top gear as things stand

Posted by: nickfrog

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The shifter feel doesn't seem right so I am blaming too much friction despite a brand new outer too

Well the routing on yr original pic was very tortuous - presumably better now?  Has anything kinked in the last 10cm ?

If it is in the right place then an Avid Rollamajig might help. 
Avid designed it to assist with dodgy cable routing but it helped Shimano more than SRAM - so it got discontinued. 

They do turn up NOS and might well improve your cable routing - though I agree the mech looks too far clockwise. 

Shifting gone again. Never seen that before 😂. Almost funny. I know what everyone is thinking and I agree, it has to be human error. But when you try everything several times...

B screw is a possibility though. I am running a 52t and I am pretending it's a 51t for B screw purpose to comply with the engraving at the back of the plate. Reason being I can't compute whether it should be different and in which direction...

Chain length as per Shimano recommendation and no fouling. Sadly!

Remove the cable and zip tie externally and you can improve that routing...

^ sounds like a plan. Will do and at least I will know if that is the root cause!!

Cheaper than to buy a GX mech! Which I was about to do.

Got a pic of it when built with a working mech? Or another similar bike with a mech fitted?

Any chance of a bit of a strand of the old cable remaining in the shifter? I had this once with 105 levers and that caused  intermittent shifting issues 

So my two pennorth.... If the angle of mech is really ok(?).. Is the cable outer too short? The bit from frame to mech looks v short and is there enough slack to cope w suspension movement which might give you some ghost shifting?

Or.... When you swapped out the bb did you mix up the cable routing at all? (though looking more closely it doesn't seem to go round the bb)

Don't know what cables you've got there but I have found a proper Optislick set makes more difference to Shimano shifting than it really ought to. If it were Sram any old cables would work.

Clutch too tight?

are the wheel bearing ok?

Its a sign mine need changing when shifting starts to wander

I've had similar issues with a CX bike, the cable routing is pretty tortuous and *incredibly* sensitive to cable length.

Tried it with one of those special bendy cable outers and that was even less of a success!

Make sure the outer cables are all cut perfectly flush and straight. Optislick ones work well but if you don't want to buy new ones, just use some chain lube (not wax!) on the current ones.

Or get around it all by fitting an electronic groupset! 😉

What’s this mark on the hanger? If it’s a stone chip it could be affecting the derailleur movement.

B-tension adjustment?

Thanks all. The mark is just grease. The Deore mech and shifter are brand new with an Optislick cable too. The wheels are new. The cassette is almost new. Clutch on or off makes no difference.

I have now re routed the cable through a piece of new SP41 outside the bike in a straight line. Problem the same. Impossible to properly index. It will be perfect up and down the cassette and 60 seconds later it will just not shift in the middle of the cassette or start making silly noises.

Makes no sense. I really do not like the feel of the shifter at all. That's my hope, a dodgy new shifter. Will transplant my shifter from my other bike which has exactly the same set up and working like a dream.

SRAM chain length might be the issue. But what do I do ? It's spot on by Shimano recommendation so do I cut it? Extend it?

I could swallow my pride and take the bike to the LBS. I have no idea what they will do apart from saying the parts are not compatible...

I have kind of given up but it's my girlfriend's bike so not great.

I genuinely think installing a 12 speed transmission is a piece of cake, always been. Absolutely gob smacked.

Reinstall the Sram shifter to find out if the shifter is at fault?

What frame is it ?

Tried an SLX shifter and then the old NX shifter. Same result. The frame is a 2020 Canyon Neuron 7 (women).

Playing with the B screw in different directions didn't help but I am aware how incredibly sensitive that is so will try again tomorrow, which is another day I believe 😂

They sold the 6.0 with Slx/XT so it should work. Any difference with clutch on or off? I’m guessing the angle of the photo makes the mech look at the wrong angle

Good point and I am having the same issues with the cable away from the bike entirely so it's fully compatible. Clutch position makes no difference. Will be very finely tuning the B screw tomorrow and if that fails will add a couple of links and if that fails will cut the chain. Can't think of anything else 😂. 

My Rascal happily runs GX cassette/chain with SLX shifter/mech, shifting is perfect.

I might also swap the rear wheel with the Rascal in case the cassette is in a different place.

Is the cable terminated as above?

Photos of the mech from the side to see the gap between the jockey wheel and cassette; with the chain on the largest, second largest and smallest gears so we can see the chain length and b tension is looking like. 

Sure. Photos from the non drive side presumably?

After 2 hours of tweaking b screw and indexing (I have never had to spend more than 2 minutes tweaking 12 speed to get near perfect result and most of the time it's excellent before the tweaking), I can only get one end of the cassette shifting well. There must be something seriously wrong. 

Photos is my last hope. GF a bit pissed off now and I don't blame her.

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Posted by: nickfrog

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There must be something seriously wrong. 

Disconnect the cable from the rear mech, hold the end of the inner in your fingers, then try shifting gears. Does it pull uniformly through the entire shift?

I'm wondering if it has got snagged somewhere on its internal routing voyage...?

Also, apologies if that's a bit basic and you've done all that 4 times already... 😉

Thanks, every little helps. I tried that and even used a secondary SP41 outer outside the frame to no avail.

And also no idea why the other requested photos are not showing, or maybe they are 😂. Not going well. This is unreal. 

I have to say that selfishly it's my ego that is the most bruised for now 😂. 

Useful diagram that cerrado-tu-ruido, I need to check the derailleur I cabled up on Wednesday evening now, although it worked OK in the stand. 

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[url= https://nl.imgbb.com/ ]file hosting gratis[/url]

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The cable isn't slipping or getting repositioned so the inner cable has no tension on it?

No, sadly. I am hoping that the requested photos above will help. The B screw is set as per the 51t curve at the back of the mech. Going either way half turn by half turn makes no difference.

Could anyone suggest anything? Is that even possible? I run the same setup on the Revel and it's perfect. Is it all down to the way the hanger sets the rear mech angle? Or could the rear mech itself be faulty ? (brand new Deore).

Looking at the photos I would say the chain is slightly too long so the b tension is putting the jockey wheel in the right place.

Before actually shorterning the chain, folt it over to the length you want with it on the largest gear and move the suspension through the full travel so make sure it doesn't over extend. Let the air out or take the shock out. 

Check mech hangar is correctly fitted, tight and alignment is true. 

Then set high and low stops with out the gear cable.  Then fit the gear cable, set b tension ( on the closer side and dial in the indexing. If it catches shifting to the bigger gear add some b tension but run it as close as possible. 

Don't forget that the bike being in its travel will change the chain length and thus the b position, normally bring it away from the cassette.

Thank you so much. I know my limits and I would probably have thrown the shock through the window had it been in my hand 😂 (I am serious actually as 6 hours to index a push bike is not normal).

So I removed 2 links and reset everything from scratch. The symptoms are still there but all to a lesser extent.

I still have to choose between the top and the bottom of the cassette like if it was a bloody Gripshift.

I am working the B screw quarter of a turn at a time but it gets complex because I also have to change the indexing permanently. 

I am tempted to cut the chain again but the mech is probably under enough tension in the biggest sprocket.

I'll leave until tomorrow as this is really getting to me and I need a clear head. I wouldn't wish this to my worst enemy although I don't think I have any.

Thank you all.

If b tension is changing indexing then mech hangar must be bent.

Edit 

Or mech is bent. 

I know you said it's not the mech hanger, but have you actually checked it using a straightening tool?

Is there any play in the cassette when the wheel is on? I've had a Mavic axle come loose when circilp on the NDS end slipped.

Empty shock of air and compress fully to make sure the chain is long enough at full stretch, then add some air so the shock is sitting at the desired sag level and then set b-tension, once that is set, adjust cable tension and make sure cable is tightened snuggled (and fitted to clamp bolt properly). It is best to set that while bike is in sagged position.

Top up shock to desired pressure and try that.

That assumes mech hanger isn't bent.

It stands to reason that the hanger is bent I agree. I have tried with my own rear mech and that's not it. The bike wasn't ridden or knocked about before the old neglected SRAM stuff (which was shifting with absolute perfection) was replaced  BUT perhaps it was already bent and the SRAM stuff just didn't care. I don't have a tool to check so will give the bike to the LBS if it doesn't end up in a skip first 😂 

Remove the hangar and put it on a flat surface...any gaps or bits sitting proud?

I feel the need to try and help. But not sure i know as much as you. 

But i do own a neuron cf 8. Like many bikes the shifting is to some extent affected by axle tightening. Mine worked better after my lbs tiff my off for over tightening the axle. It might even change the angle of the mech, like a bend derailleur. Thinks it’s only 6Nm.

You are using a shimano shifter? I thought the block spacing is the pull ratios are only similar

Will take the hanger off and have bought the Toopree fake Park hanger tool for £20 or so.

Using the SRAM shifter now. Will check if wheel too tight.

Ta very mucho.

Got the hanger tool and the hanger is perfect.

While checking however I noticed the cassette was bent which the tool confirmed. The 3 biggest cogs are bent. Not easy to spot without the tool but pretty obvious with it. Not sure they can be straightened.

I'll swap my own recent GX cassette to her bike and ordered a £499 X01 groupset off Jungle/eBay for my troubles😂. 

Posted by: nickfrog

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Using the SRAM shifter now.

You're using a SRAM shifter and a Shimano mech?

You're using a SRAM shifter and a Shimano mech?

It works for (non-T-type anyway) 12speed.

Posted by: sl2000

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You're using a SRAM shifter and a Shimano mech?

 

I'm doing it the other way around, shimano shifter/sram mech - works fine.