I have broken Google trying to find the exact issue I am having so hope you lot can help.
Equipment as above and setting up without cable or chain allows perfect alignment with small and large ring. I put the cable in being careful not to pull and move the mech. Shifts across all but the big ring. Loosen the cable tension a bit, and I lose the click for the first shift from the small ring. Take out cable and check again and I can line up big and small. Cable back in and it won’t reach big again.
We are talking between 2&3mm of further movement for it to reach. It’s a long cage XT mech, brand new, with XT shifter.

Thank you……I hope!

I’d check the high/low adjusters on the mech with the drivetrain all connected, same with the B screw, i have a 12sp XT with a garbaruk 10/52t and not had this issue, so it can do the range.

If the mech adjustment doesn’t work, check the cables, is the last bit too short and gets overly tight when going into the big ring, do you need a little more outer to not foul when maxed out in the big gear?

Am I misreading something? The cable won’t pull the derailleur far enough to shift into first gear so you slackened it? I’m confused but if that’s the case you should be adding preload to the cable, not slackening it. From memory, it helps to nudge the derailleur inwards a little before tightening the cable in place. Unlike something like an old 9sp Sram derailleur where you just pulled the cable tight, tightened the clamp bolt and you’re good to go.

@walleater. Will try and explain better. So no chain on using hand to pull cage down so it doesn’t hit the rings. Sits nicely in line with small ring and clicks through all gears fine. The problem is the position of the jockey wheels after the last click when they should be in line with the largest ring, they miss by approx 3mm. The cable hasn’t been able to pull the mech far enough across.

@argee. Maybe need to put it all together with chain as you say. Was trying to follow a set up guide which set it all up without chain, and even cable initially, and it was all going well until the cable was introduced. I always have issues when I just bung everything together so thought I would take a different, and more methodical approach, that went well then 🙂

So it lines up once cable is fitted in top gear (smallest sprocket), clicks up seemingly in line with each sprocket initially but by the time you get all the way to the biggest it’s 2mm short of being in line with the biggest sprocket? Assume you have fitted chain and adjusted indexing and this issue is after that.

The first thing I would check is hanger alignment. I had a similar but opposite issue and found it required a bit of trial and error with hanger alignment to get it just right.

Also check cable is correctly routed. If that’s wrong then cable pull per click is wrong.

The issue you describe doesn’t sound like one of B tension or chain length, but I would make sure those are right too. B tension needs to be set just right, and done at sag. My method on chain length is essentially to go looking for the longest chain I can get away with at the outset, so top gear (smallest sprocket) and set it to the longest it can be there without being slack, then you have the option to shorten it from there, but I haven’t. Because you can’t make it longer (well, you can, but you know what I mean). Unlikely, but it could be that if the chain is too short then the extra tension in the system affects both running and shifting down in bottom gear. If you’ve just fitted a 52 tooth cassette in place of a slightly smaller one then chain could be short.

I cannot really help but I can confirm that I am running this set up (with long cage XT mech) and it works

From memory I think with Shimano the guide pulley should be (if looking from the back) slightly to the left of the smallest cog, but it’s only a fraction. Might make a difference..

Also with cable on have you fiddled with the limit screws to see if that allows you to get into the big ring?

I’m rapidly falling out of love with 12sp it’s a very fine line between working and not…

@MartynS, I am rapidly falling out with setting up 12sp I can tell you. The thing is that there is nothing stopping the cage going to the big ring without the cable attached, it is only when the cable is added it refuses to move across. This tells me it is cable related and not mech tweak related but I will be fecked if I can sort it.

No point even putting the chain on if I can’t even get the thing to work without it.

have you shifted the shifter to the highest gear before tightening the cable?

has the shifter been confirmed as working correctly?

are there any kinks in the inner cable?

i’d put the chain on to see if i could get it working fully assembled

You need to fit the chain if you’re still working without it. Chain length determines where the cage is in any given gear. Then if the top jockey wheel is too close to or hits the cassette in the biggest sprockets more B-tension will move it further away.

Apologies if I’ve missed the point.

@lucket, You might have missed a bit of the point, but to be fair, I didn’t labour it. My normal way to do this would be to throw all of the stuff on to the bike and go at it with the cable and chain on. I never have much luck and it usually ends with hours of you tube videos and frustration. This time I did YouTube first and the mechanic was explaining how it is easier to set it all up before you add the chain/cable, and just fine tune, if you need to, once the chain & cable are on.

So I did this, and set it up with the upper and lower screws so the jockey wheels were lined up with small and large ring, feeling good at this point, added the cable, boom! problems. I will get the link to the video at the end of this but for the moment the guy was stating that you need to avoid pulling on the cable as you fit it as it will move the mech out of position and undo what you have just done. I found it rather hard to get decent tension when carrying out this step to be honest. Anyway, that’s what I was trying to do, now I am going to be back where I always am as I add the chain and find it doesn’t shift 🙂
Linky Link

As above, are you sure the cable route into the derailleur is correct. It’s not entirely intuitive. I routed my XTR12 wrong the first time I did it and it would work fine without the chain, but not with it.

@Daffy, I will double check, looks fine but will compare with my other (shop built) bike that also has an XT mech.

Update for anyone vaguely interested in the trials and tribulations of a home build. I put the chain on, it shifted up to the penultimate ring, thought about going into the last ring………………………..and then fell off the front chainring due to the chainline. Turns out to can get away with non-boost cranks with 10sp but not 12sp. Another bunch of cash dropped on a new boost crank and chainring. Anyone in the market for a 170 non boost crankset?

That doesnt make sense. I might be wrong but doesnt boost put the chainring further out. Non boost, if anything should work better with the lower range as the chainring sits more inboard so a better chainline.

Have you got your BB spacers correct? You could be pushing everything too far drive side with too many spacers. If so, boost chainset is just going to get worse!

I always end up spacing my boost cranks / ring further in board than recomended for that exact reason. I spend more time climbing than sprinting so take the quieter inboard set up!

@silasgreenback, I am so confused now. The BB was fitted by the frame manufacturer so all good I assume. The boost/non-boost thing is all I could put it down to as it is the only thing out of spec.

This bike building lark used to be so easy.

If the BB was fitted by the manufacturer you’d assume it’d be right. But yeah, so many standards and specs nothing seems to play nicely first time anymore.

I always build my own. Currently at bike build no.9 but my last one – Bird Forge, I couldn’t spin the cranks as they kept hitting the chainstays! But thats the Race Face cranks and really narrow Q factor – how wide the pedal interface is. Had to adjust the spacers on the bottom bracket and cant run neoprene protectors as the gaps too narrow. All sorted now though but “outside normal spec”.

I’m still 11sp but 1mm spacer on the cassette, boost frame and wheels plus non-boost cranks/ring, 1x 2.5mm spacer on driveside BB shell (73mm shell i think) and all fine.

Falling off into the frame in with chain in biggest sprocket would be chainring too far out. Falling away from the bike in highest gear would be chainring too far inboard. But it’d have to be wildly out if its all new stuff.

Hate to say it but if your cassette is further towards drive side (boost) and non-boost cranks stay inboard compared to boost it doesnt sound like cranks. Should be falling off on the smallest ring or really noisy that side. But perfect in biggest ring.

Bit of background reading https://www.wolftoothcomponents.com/pages/boost-chainline-and-chainrings

Measure centre of seat tube to chainring for your chainline. Then see what manufacturer spec is for a guide. +/- a mm or two wint make much difference in my experience. As i say, i fine tune to run smaller chainline for quiet climbing!

Sounds to me like you need to strip it off and start again.

It doesn’t sound like the crankset is the problem. The only reason to go for boost cranks is for chainstay clearance with the crank or chainring. Or tyre clearance with the chain.

Ive not fitted a garbaruk before. Are there any spacers that may have been put in the wrong place?

Take the mech off and check hanger alignment. With a proper tool. Not by eye.

Measure chain properly following shimanos measurements.

Page 10 of this document…

https://www.google.com/url?sa=t&source=web&rct=j&url=https://si.shimano.com/pdfs/dm/DM-MARD001-00-ENG.pdf&ved=2ahUKEwjgtPf6j8v4AhWbSkEAHRvzDIoQFnoECCEQAQ&usg=AOvVaw3AX5vw6a-u1om9kQaFS9Wg

Fit derailleur and thread chain, then join chain.

Adjust H limit screw so the chain is in line with 10t.

Then manually push the mech to the top while pedalling slowly to roughly find the lower screw position making sure it won’t jump the chain into the spokes when you shift with the cable. Attach cable (check above doc for cable routing) and shift upto the top of cassette. Fine tune L limit screw and then B tension using the line on the back of the derailleur cage.

Now finish tuning indexing with the barrel adjuster.

I’ve never had any issues following this method.

@Chrisdw, went back to the start as suggested but ended up in the same place but thank you for the in depth response, it will be helpful in the future. I am now going to have to go back a year or so and see what was done to the rear wheel when it was adjusted to fit a boost frame from a non-boost. Maybe something here will shed some light. Tempted to just whack the 10sp old cassette on and just get it dont without the bling but that will kill me after so much waiting time and financial investment in the parts.

Just one other thought.. it’s definitely a 12 speed shifter is it?

It better flipping had be 🙂 Anyway it isn’t even the shifting that is the major issue now it is the chainline and the fact it won’t stay on the front ring when in the largest ring at the back.

Is the chainring round the right way? Is the chain on with the correct side (shimano writing) facing out?

As above, check cable routing through the mech.

I tend to set up the low screw so the nearest jockey wheel is just fractionally inboard of the smallest sprocket with the chain on. Alternatively use the barrel adjuster to find the point where it just skips up onto the next sprocket, then back it off a little bit.

12spd indexing can be quite fussy, though. I generally aim to get the shifting perfect in the first few gears, up and down, and then it’s usually OK all the way up the cassette.

@Martinhutch, tried both a standard Shimano ring and the original intended ‘bling’ Superstar ring and neither would keep the chain on, both were fitted the correct way (I assume graphics on outer side is correct anyway) The chain is KMC so not directional.

I am starting to think it might be something with the rear wheel and position of cassette now, but I am running out of ideas so probably heading in the wrong direction. Bike shop will be the next stop I think

Hi @johnjn2000,
Can you confirm you’ve checked the cable routing in the rear derailleur? A few people have mentioned and I don’t see a reply from you.

I ask as I had really odd problems, was cursing 12 speed and had actually just put the cable in back to front on the derailleur. It’s quite easy to do! This was also with XT and a Garbaruk cassette.

Stu.

If it’s a non boost hub that has been converted to boost, does that mean the cassette is a long way left compared with where it would be on a proper boost hub? As well as affecting chain line particularly badly in the lowest gears I can see why that might upset the mech.

BTW I have both Garbaruk and shimano cassettes and found there to be no difference in the principles of setup, so I think it unlikely the choice of cassette is the issue here. My Garbaruk has no spacers.

Yes, some of the boost (148) conversions add a longer spacer on both ends of the axle, this is a bodge and pushes the cassette over a couple of millimetres, This upsets the rear mech parallelogram geometry and means that the last few degrees of swing don’t move it quite as far as they should.

Saw a similar issue when people didn’t know how DM rear mechs worked and they left the b-link on. Not only does it push the mech back and down (which isn’t a huge issue) but they push it out a few mm, which is a significant issue…

@u02sgb, yup I have triple checked the cable route and it looks fine. Just fitted a new boost crank with new chainring and guess what……………yes, same problem. It is now looking more and more likely to be the Wolf Tooth boost conversion causing the issue which is another expensive fix FFS!

Doubt it would be the boostinator, they tend to put the 6mm on the disc side, hence why you have the rotor adaptor to space it for the caliper.

Wolftooth boost conversion is all on the disc side so the cassette should be on the boost chainline, right?

I’ve happily run the hope boost conversion which doesn’t correct the chainline- 11 speed, admittedly, so not as much of a stretch, but the mech handles it to the extent that I’ve never noticed a problem.

Just to clarify now that the original issue is kinda fixed. The new problem is the chain line meaning it falls off the front ring to the inside when on the big ring at the rear.
I am now frantically listing all my spare parts in lieu of a big bill for a new wheel or something equally expensive

It’s heading to the bike shop today, going to drive by and throw it out of the car Grrrrrrrr

OK, I hesitated bumping this due to embarrassment however there may be others as daft as me in the future so it could help save someone a few quid.

The original problem of not being able to get it into the large ring was fixed once I added the cable and chain together. Ignore the bloody YouTube tutorial that tells you it can all be set up without a chain.

Now for the embarrassing bit. When you have just had one major issue and another comes along immediately afterwards, don’t jump to the conclusion that they are linked (pun intended). I got so fixated on the workaround for not having boost hubs being the root cause of all the issues I didn’t stand back and think differently. I subsequently spaffed £120 on a new set of SLX boost cranks and a new chainring, this didn’t solve it, the meltdown continued so I sent it to the bike shop. Turns out the reason for the chain dropping inside the front chainring was the chain line to a degree, but the major influencer in this issue was the fact I hadn’t fully engaged the quick link…………………….arggghhhhhhhhh. I had the bike in the stand with no back wheel or pedals so didn’t do the jumping on pedals thing to click it into place. Spacer is now swapped around to give a decent chain line and the quick link is fully engaged, and my bank account is significantly lighter so I am having to sell stuff. Anyone want any children?

I’m sure most of us have done worse. <Looks around nervously> No? Just me then?

Anyhow, now you have brand new cranks, you’ll be needing a new frame to build up. 🙂

Good that you got it sorted, shit like this drives everyone nuts, it’s not just you.

@martinhutch, new frame all built up and ready to roll 🙂 It would have its own thread if i could post photos on here but it would be a bit bland with just words describing it

upload them to postimages.org 🙂