Shimano Xt M8000 Chainline Issues

It’s hardly a real problem is it??

Probably not at all but really happy my sram setup doesn’t do stupid shit like that it would probably put me off for the price of a new set of running gear

I also remember reading somewhere that this can improve once you’ve put a few miles on the chain, as it will have a bit more lateral flexibility once used a bit.

I have just built up a 1 x 11 setup using SRAM 10-42 cassette, SRAM PC-X1 chain, superstar 30t chainring on SLX double chainset, M8000 mech and shifter. Haven’t ridden it yet, but can back pedal forever with no dropping off the 42t.

The 30t chainring has built in spacers (2mm I think) which probably helps…

I have recently gone 1×11 too and am having chainline issues . I am using the new xt 8000 1x chainset and my chainline is worse than my friend who used his existing XT chainset , we are both using 32T Absolute black oval chainrings . I was wondering if the Shimano casette which has the 32 sprocket dished gives a different chainline to a Sram casette.Anyway my once used Shimano XT chainset and Absolute Black chainring is going up for sale this week and I am going to use my old XT chainset as it appears to give better chainline .

XT8000 2×11 Boost here and having no problems.

Ramsey Neil – just add some chainring spacers. Depth req’d will depend on chainring used. Wheels Mfg do various depths. Better than losing money on a nice chainset and chainring.

Thanks for the tip sillyoldman but I don’t expect to lose any money as I got the chainset at trade price . I am pissed off however that the dedicated XT 1x chainset gives a worse chainline than “bodging it” by converting a double to run as a single .

Pivot Mach 6, 1×11 XT M8000 ultegra chain. same problem.

If you put your bike on the stand and pedal back slowly you should notice that it drops on the shift ramps of the cassette.

Its got better as the chain has worn, but IMO its just poor design on the crank. Chainline on mine is straightest when in 8th gear, should be straightest in 6th. I’ll try a different chain next time, hasnt really been an issue as I dont tend to back pedal. 🙂

Ramsey Neil – have you tried it with the XT ring? Any better?

Replacing SRAM chain fixed this problem for me. Also moved the spacer from the drive side. 2012 SC Tallboy LTc. New m8000, full group, 2x cranks. No backpedal problem with big or small chainring anymore. Thanks all on this thread!

Ramsey Neil – just add some chainring spacers. Depth req’d will depend on chainring used. Wheels Mfg do various depths. Better than losing money on a nice chainset and chainring.

On the M8000 crankset the chainring bolts to the outside of the spider so spacing it would make the chainline worse not better .

Ramsey Neil – have you tried it with the XT ring? Any better?

I don’t have an xt chainring as the chainset comes without one .

I wouldn’t say it’s necessarily the chainset. I’ve just built a 1×11 on my santa cruz using XT for the back end with raceface aeffect cranks and a hope bottom bracket and a 28t chairing and I’m having the same problem. 😕

Ramsay Neil – the chainring doesn’t bolt to the outside of the spider – I have one. It’s also pretty clear from pictures that it mounts to the inside of the spider. I used spacers on mine to alter the chainline.

Turbo1397 – RF uses the widest chainline out of all the options out there (except Boost specific jobs).

@sillyoldman.. what would my options be?

Worth looking at alternative chainring brands – some make a point of “correcting” chainlines. I find around 48mm works best for reference. RF is 51mm.

See http://www.wolftoothcomponents.com/collections/chainrings/products/direct-mount-race-face-cinch for an option.

If you’ve got a threaded BB, you can take the cheaper route of moving a BB spacer from DS to ND, but then your pedals are offset to the ND side… Guess you could adjust cleats to correct.

Sillyoldman you are correct , I may try some spacers.

Turbo1397 have you adjusted the spacers on the cranks? I think they come at their widest setting out of the box. You can pull them in to 50 using the spacers on the cranks.

Also Shimano now supply BBs with variable sized spacers which allows a little more fine tuning.

I’m using a threaded hope bottom bracket.. my LBS has assembled it.. It looks like there’s a spacer in there..

The cranks have spacers too (incase you didnt know).

Going to look into this today.. so what is causing the chain line issues, will it be the cranks. As I’m only running XT stuff at the back would it make any difference if I ran a sram rear cassette?

It is your chain line.

You can measure the chain line of your bike (google how) and you’ll find that it will likely be around about 46mm. Depending on if you run a 3x, 2x, 1x crank, the crank will offer a different central placement of the front chain ring in relation to your rear cassette. Some manufacturers do state their chain line on cranks, which is handy but you still need to calculate the rear cassette chain line and then align the two.

The goal is to have the front chain ring align to the centre of the rear cassette (you can’t accurately eye ball this, so measuring is required). If you get it bang on then it’s sweet shifting, back pedalling nirvana, if you get it really close you’ll be good, not close enough and you’ll have exactly the same result that folk are referring to here.

Shimano make their new 1x cranks with a 51mm chain line (i recall) which is plain useless. Some NW chain rings have 2.5mm spacers fitted. If you then offset one of the spacers on your BB, or the only spacer on 73mm BB shells (don’t remove them) to the non drive side, you will gain 2.5mm (5mm with the ring) towards your ideal chain line.

Note, the B screw needs to be backed off a lot, way more than you might suspect but it does/ will work out, regardless of the branded chain being used.

😀

Cheers binno. I removed the spacer on the drive side and it is better.. not perfect, but better. I’m going to ride it a bit and see how it is.. as everything I new.. chain and all.

As I’m only running XT stuff at the back would it make any difference if I ran a sram rear cassette

Yes, but not so much I would bin a Shimano cassette/Freehub just for the slightly better chainline. I would to get the 10T cog though 😉

Sram Chainline is 48mm, Shimano 50mm, Raceface 51mm, and a lot of aftermarket ring makers go for 49mm.

They are all a compromise. Some bikes require a chainline of 50+ to work with a 34T+ ring size, hence Shimano and RF going for 50 and 51. No point in a better chainline if it doesn’t fit. I saw a Cotic Soul today with a 34T XT set up which didn’t have much room between the ring and the DS chainstay.

Shimano’s approach means that it’ll fit anything (within reason) and can be optimised using chainring spacers where appropriate/possible.

Is a simple fix for all the above to just use the middle chainring position on a triple chainset – or is it that I’m still on a 26er 😉

Not really – middle ring is only a 50mm chainline which isnt helping much and is wider than SRAM 1x (Its actually the same 49mm as SRAM 3x cranks middle too). On new XT cranks though if they fit together then a middle ring on a triple combined with the 11 spd offset ring would be an improvement. The simplest current solution for the best chainline you can get would be SRAM cranks and 10 spd or XD cassette (rather than shimano 11) or other cranks with a 49 or less chainline ring installed, and a 10spd or XD cassette.

I had high hopes that the new XT single cranks would address this with a shorter axel length or offset chain ring tabs. Fingers crossed it will happen in the not to distant future.

Just incase you mis-read my original comment, the chain line specified by the manufacturers is not the actual chain line you require in order to have the front ring aligned to the centre of the rear cassette. Which is what you’re ideally looking for.

So yes, in my view, with outboard style Bottom Bracket cranks, a converted triple is still the best solution. I very much doubt anyone will tell the difference by having the crank offset by a single 2.5mm spacer, which is the best solution when running a triple. If you’re on a double / single ring crank, then it’s the single spacer and an offset chain ring (iE: 30T Race face NW / 32T Absolute Black with built in bolt spacers) that you need to use. Although you could also use longer chain ring bolts to shim a regular chain ring inboard.

IMO it’s not just a case of getting super smooth and quiet gear changes from every cog, it’s also about drive train efficiency and reducing rapid wear by crossing the chain further than intended.

I do love a perfect chain line.

So how does a rf aeffect single ring work with a XT x11 boost hub. If the optimum boost chain line is 52mm, then a 51mm rf ring seems to be ok. But if I go for a absolute black cinch ring, is this dished to move the chainline back to 49mm, so maybe not the best solution?

Dont confuse official and optimum. Official SRAM boost chainline is 52, optimum would be in the 47-48 region – so if your bike fits it then the 49mm option is a good one. Its what I would run on a boost frame.

So by that rationale if you are fitting Shimano XT M8000 1×11 to a boost rear end then you would be better off using the standard chainset not the one that’s meant for the 148 rear end . I’m confused .

Anyone care to comment on the spacing at the front chainring using a PF30 BB (giant anthem). Is it the same as an HT outboard BB?

I thought the anthem was a pf82?

So by that rationale if you are fitting Shimano XT M8000 1×11 to a boost rear end then you would be better off using the standard chainset not the one that’s meant for the 148 rear end . I’m confused .

Yep. Basically as covered on another thread current 1x chainline is derived from 3x chainlines, which were set based on factors other than hitting the middle of the cassette, and so don’t actually hit the middle of the cassette. For this reason 1x chainlines are all a bit rubbish as they are too far out now that we really do want to hit the middle of the cassette for sure. Add to that shimano 11 speed runs a cassette with a narrower chainline again and it gets even worse.

In essence a 3x Boost chainline would be 52. A 1x Boost chainline should be 49 (ish) but no-one makes a real 1x chainline for anything, although some of the aftermarket ring makers are making rings to get close. However you can use a non-boost set up to get a pretty good approximation to what a boost chainline should be on a 1x.

EDIT: I should point out that a boost chainline should be more like 47, but 49 is better than nothing.

Ideally measure the chain line with the cranks you intend to buy, fitted to a frame with the same BB standard.

Use callipers to make the measurements:

1. Measure the width of the seat tube inline with the front chainring. Divide by 1/2 and note the measurement.
2. Measure from the centre of the teeth on the front chainring (either the middle or fitted single chainring) to the outside edge of the seat tube. Keep this measurement inline and level with your original seat post measurement, taken along the the top of the chain ring.
3. Minus the measurement noted from Step 1, from your measurement made in Step 2. This will give you the current chain line position of the front ring.

The principle is the same for the rear hub, only more complicated in requiring a measurement for the width of the cassette fitted.

1. Total outside axel length hub width divided by 2.
2. Note the inside measurement of your drive side dropout to your outer lock ring.
3. Measure or google the width of your cassette and divide by 2.
4. Add Step 2 + Step 3 measurements and minus this total from your measurement for Step 1.
5. Adjust your front chain ring placement to match the chain lone number you end up with in Step 4.

Measure twice to be sure 😀

Works on any bike, single speed, 5, 9, 11 gears etc… it’s the same process regardless. Get it bob on and you’ll be in clean shift, long life drive train bliss.

Blimey! I just put the cassette on my wheel, took all my old 9 speed rings off my SLX crank and stuck a 34t NW Ring on the inside of the spider.

Works a treat 🙂