So, my brand new bike came with a shimano XT 12 speed drive train:-

10-51 XT cassette
XT derailleur
XT shifter
KMC 12 speed chain

And I just cant get it to shift cleanly across the full range of the cassette. Its either catching on the next cog up/down slightly when pedalling or if I set it to not catch it doesnt shift up/down properly.

I’m not new to setting up drivetrains and have had no problems over the last 20 years with various 8-11 speed drivetrains from shimano and sram.

So I note that the chain supplied with the bike is a KMC chain – so is it worth me getting a proper shimano 12 speed chain, or is there some other trick I’m missing to getting this working nicely?

Any pointers gratefully received…. apart from saying take the bike back and get the shop to sort it – thats more trouble than putting up with a poor drive train

That sounds like limits are slightly out to me. Or a slightly draggy shift cable that when it’s set correctly, isn’t letting the mech shift up completely? Check hanger is straight?

12-speed Shimano can be a bit problematic in the bottom gears (the back-pedal issue), but that’s different.

Personally I’d go Shimano chain – XTR is what I use as it’s the one Shimano make themselves and tends to be worth the extra for the longevity alone.

Check hanger is straight and that the guide for B-tension adjustment on the inner cage has been followed.

Jamze – limits wouldn’t affect mid-cassette performance.

11 spd had back pedalling issues with wider chainlines, but 12spd hasn’t had that issue IME. Besides it’s unrelated to OP’s issue.

Thanks, seems that from what you’re all saying is that it isn’t a case of shimano xt 12 speed being crap, so looks like a setup issue on my bike so I’ll go over the setup from the beginning one more time later on and see if I can sort it out. If that doesn’t work then I’ll get a shimano chain.

I’ve never had a drive train that so picky about setup as this one.

They are very fussy on set-up, everything needs to be spot on for it to work as smoothly as 12sp can be expected to, and chains can be critical (wasn’t a problem at the rear, but last week I had to change a KMC chain on a virtually new bike to a Shimano item as the noise it caused running over the chainring was horrendous)

I’ve found my Shimano 12 speed to be a bit more sensitive than other drivetrains I’ve had too.

They are regarded to be very sensitive to B tension. Follow the line quite precisely, experiment with small changes either side of it.

I’ve also had a very slightly sticky link and a surprisingly early need to lubricate the mech pivots.

Plus there’s the widely held view that it needs a Shimano chain. I haven’t tried anything else. Surprised a new bike came with that mismatch though if it’s a problem.

A KMC chain should run fine, I run KMC in preference to Shimano, as Shimano chains have let me down a few times.

Two things – derailleur alignment and drag between inner and outer cable, check and eliminate.

Make sure the cable goes the right way – when viewed from the back of the bike it should enter to the left (wheel side) and leave to the right (dropout side) like in the photo below. If it goes the other way the shifting isn’t quite right.

ime Nothing but a shimano chain fixed the problems on several bikes we had through the workshop we have tried Eagle and KMC chains on some bikes and had issues.

The backpedalling issue is still there and is excacerbated on short chainstay bikes (TREK is one brand that some models seems to be a problem child)

The mid spread issues are most certainly a friction problem in the shift cable or the routing this whole 0.1mm out thing on drivetrains is an absolute joke but has been made less troublesome fitting a shimano chain for us in the workshop.

WRT it sometimes hitting the sprocket next to it when shifting, we have had to replace the the B tension screw on some drivetrains to eliminate this (longer screw), one supercaliber we had in with a replacement XTR drivetrain the top pulley was nearly 2 mm above the setup line to get it shifting sweet and then the clutch had to be disengaged to not have it clunking chunkily from sprocket to sprocket

I’ve found that using the same brand of chain and cassette usually gets best/smoothest shifting assuming all is set up correctly

I’m sure someone was telling me the other day, that while all 12 speed chains have the same inner width, the Shimano is fractionally narrower and the only one that actually works optimally with their kit.

Maybe these sorts of problems are why their road stuff is still 11 speed.

I’m using shimano xt cassette, slx chain, xt mech and xt shifter with a Northshore Billet chainring designed for shimano hg 12 speed.

I found it very fiddly to setup and in the stand if you back pedalled it’s dropped down the cassette. However once it’s worn in a bit it’s stopped doing that as far as I can tell.

It does now shift pretty nicely when clean – but when it gets a bit mucky I don’t find it very good.

It is sensitive to hanger straightness and how tight the final bit of cable outer is – I had 4 goes at the length of the cable outer before I got something decent.

I’m keeping gx 11 speed on my new hardtail – in comparison that just works and doesn’t need adjustment / doesn’t go terrible when it gets muddy.

I wonder if 12 speed is a step too far in terms of spacing of cogs. Although that said I found the new style 11 speed shimano mech a pain to setup as well.

I wonder if 12 speed is a step too far in terms of spacing of cogs

Nah, it works fine with SRAM GX, X01, XX1.

I’ve gone through the set up process from scratch (again!), seems a bit better shifting in the workstand , but wont be able to pass proper judgement until I go out and ride it.

It really is a picky thing to get working, if this doesnt work I’ll get a shimano chain. If that doesnt work, I guess I’ll put up with it until something breaks then either go SRAM, Shimano 11 speed or sram AXS

Echoing whats already been said above, it can be a bit sensitive, it came on my newest bike and I had a couple of issues as well.

Mine has a shimano chain and that would be my primary candidate for your problems. Are you completely sure it’s a shimano spec 12 speed chain as shimano and sram 12 speed chains are different, the shimano has narrower inner plates so a SRAM spec chain would hang up on teeth as you are describing.  The issues I had were down to the cheap and nasty BSO spec Jagwire cable and outer they used having buttloads of friction in it resulting in a heavy feel at the lever and slow shifting.  Changed it out for SP40 and Optislick cable and it has been smooth, light shifting ever since.

It really is a picky thing to get working, if this doesnt work I’ll get a shimano chain. If that doesnt work, I guess I’ll put up with it until something breaks then either go SRAM, Shimano 11 speed or sram AXS

I wouldn’t give up on it too quickly, unless there are issues with your specific frame/gearset combination I have found it to be an excellent group.  I came from a SRAM eagle setup on the old bike and while it shifted very well, the shimano stuff is much much better shifting under load, much lighter feel at the shifter and the multishift is great.Once i switched out cables as mentioned above it’s been flawless with no missed or nasty shifts. I have found it to be more resilient to mud and bad weather and it’s wear rate seems to be similar to SRAM as well.

Not sure why others find it sensitive to set up – mine y straightforward and has required no attention in the year I’ve had it. Also find it absolutely fine in the mud.
Genuinely the best shifting group I’ve ever had inc XTR Di2.

Maybe those having difficulty have hanger geometry that’s outside Shimano’s spec? Dunno – seems odd.

Simple things to check:

Make sure the mark on the back of the mech aligns with the 51t of the cassette.
Make sure the cable routing is good and there is enough slack going into the cassette to allow full range.
Make sure the rear wheel and cassette are on properly.
Make sure the mech hanger isn’t out at all.

I find SRAM 12 a problem, but also found my new XT 12 is also a bit off from the shop, just a quick check over has corrected most of it though, i think 12 speed is as far as they’ll go for a while as the difference between 11 and 12 for keeping right is pretty big

I’m not sure why some bike companies are specing non-Shimano chains. I’ve read the inner width is different, as above, also read the link length is slightly different. This would confirm my findings when I tried a new Sram chain. Comparing Shimano and KMC there’s less extensive shift ramps on the KMC chain, which is integral to Hyperglide Plus working. I’d be tempted to ask the shop for a properly compatible chain.

I’ve found Shimano 12spd is rather sensitive to the mech or hanger being bent, and cable friction. Otherwise, best shifting I’ve ever had.

It’s an orbea wild fs m-team ebike, so not a cheapo bike , i think the reason they use a non shimano chain is because its an ebike, they use the kmc e bike specific chain.

The little mark on the back of the derailleur cage is not quite lined up as per the shimano instructions but it’s at the limit of its adjustment, it won’t go any closer, so maybe this combined with the none shimano chain is the cause?

I’ll need a new chain soon enough anyway if the story of ebikes wearing out chains really quickly is true.

The little mark on the back of the derailleur cage is not quite lined up as per the shimano instructions but it’s at the limit of its adjustment, it won’t go any closer, so maybe this combined with the none shimano chain is the cause?

Sounds to me like the chain is too short.? Chain length is a particular issue with 12 speed and I found that it has to be a couple of links longer than you might think.  The formula that shimano stipulate is a particular wrap around cogs and then add either 1 or 3 links i think.  I have read several articles that suggest that adding the higher number of recommended links is the way to go and that it almost always results in better shifting.

Full Shimano XT 12sp here and runs sweet – no back pedalling issues, no skipping or noise. Shifts cleanly under load. Overall been really impressed with this groupset.

I did find I had to get the b-screwn dialled in, but that only took a few minutes – and have found it’s a bit sensitive to the mech bolt coming loose in the alps 😀 oddly with the mech half hanging off its shifting turns a bit poo.

^^ This

Interestingly I have been running XTR 12 speed for almost 2 years and had no problems. But I have recently put XT 12 speed on my new ebike and the derailleur has come loose twice. You really need to get it tight.

Unfortunately bikes aren’t always set up correctly, bike mechanics make mistakes. I always check everything and re do it myself so I know it’s right, hanger alignment tools are cheap on ebay, 12sp is definitely more touchy about hanger straightness, shimano chain is needed to benefit from HG+ shifting but the chainring has to be compatible for shimanos 12sp.

Mine was pretty simple to set up, i did have a couple of minor issues at the start but that was because i didnt read the instructions properly.

The key for me was making sure the line on the derailleur was exactly lined up with the 51 tooth cog, after i got that sorted it was plain sailing.
Mine wasnt set up by a bike shop as i was building up a frame myself.

Chain length shimano say wrap round and add a certain number of links depending on whether a hardtail/full suss or whether it falls on an inside link or outside.

I found it easy to accidentally tighten the mech bolt up with the b-screw plate not quite butted up against the stop on the frame.

It needed loosening, mech swinging forwards a bit, then tightening again.

It caused me a bit of head scratching, not sure if it’s the issue here on not though.

Been for a quick ride , its better but still not quite right, will check some of those other points (especially the one about chain length, and the mech bolt tightness above)