Afternoon folks,

I’ve searched the net but found all sorts of contradicting stuff. As such, I turn to the knowledge of the STWers.

Currently got XT M785 setup and my chainrings are worn so it’s time to consider 1×10. The only thing that concerns me is getting the right chainline and making sure the my cranks are compatible with the appropriate chainring etc

What exactly do I need to do to my crankset?

Is it just as simple as….

New chainring (think a hope Narrow/Wide would do the trick)

How do I go about getting the right chainline? Different bolt lengths, spacers or something?

Cheers people

If it helps, my chainline is straight when in the big ring and the 8th sprocket at the back.

Assume i’ll need a way to shuffle the chainring inwards a little to make it more central?

Remove old chainrings, front mech and shifter.

Buy a narrow wide chainring of appropriate number of teeth, 30, 32 or 34 depending upon where you commonly ride and/or leg strength.

Buy single ring chain bolts

Attach new chain ring to outer tabs of your XT crank arm with new and shorter bolts. As far as chainline goes, you can shim the chainring, although I suspect you’ll be fine. Just check the chain is straight when in the middle of the cassette.

EDIT: you could remove a spacer from the drive side of the bottom bracket to move the chainline in, and in which case, you may need to put it onto the non drive side to ensure the BB length is okay, but I’ll be prepared to be corrected on that.

Buy a new cassette and chain. And new rear cable while you’re at it to save hassle on your first ride.

Set chain length by routing through rear mech, largest sprocket on cassette and chain ring so that the mech is not at full stretch and not too un stretched. If you ride FS, then do this with the suspension fully compressed, ie let air out of the rear shock.

Go ride and figure out whether you need a clutch mech and/or chain device.

Have fun riding your bike 😀

All I did was move the bb spacer to the non drive side and it seems fine.

Alas my questions have been answered! Cheers dudes

Erm, almost sorted.

Just took my cranks etc off and there doesn’t appear to be any bottom bracket spacers? Is this normal? Ive got a shimano press fit BB71 bottom bracket.

What’s the width of your BB shell?

IIRC, 68mm shell normally requires 5mm on drive side and 2.5 on non drive side. 73mm shell would require one 2.5mm spacers either side. I’m not familiar if there are wider shells that require no spacers.

One 2.5mm spacer on the RH side only for 73mm, if you have a bb mounted front mech or chain guide you have none.

However, pressfit is different, 87/92mm IIRC, no spacers for 92mm.

Yep its a 92mm width. So guess it’s just some spacers/washers to shim the chainring inwards a little

Don’t bother. I ran 1×10 on the outer position of an XTR Race double, was fine.