I’ve got a triple 10 speed (2012 M780 XT) setup but want to swap out the big ring for a lovely Hope bashguard. I’m planning on keeping the 24t small ring and 32t middle, possibly change to a 34t if needs be.
Now I know the 2012 XT M780 front shifter can be switched between 3x and 2x. Will this mean that the front mech won’t need set again up once the shifter is changed to 2x (does changing it to 2x just do away with the option of it changing up to the big ring?)?

Is it worth shortening the chain and will the long cage rear mech be fine with a double and bash at the front?

check the dimensions of the bash spider against the recess on the crankarm,

i say this because if you have a slx triple, the slx bash ring wont fit in lieu of the big ring, you have to buy the slx double (this was true for 2011 anyway)

i know you put 2012 XT, but its always worth checking, as there are so many ways parts dont cross match

you can get specific front mechs for double rings, it maybe but i’m not certain, that the high stop cant be wound in far enough to take out the large ring

I have seen others with the Hope bash guard fitted to the 2012 XT triple so not concerned about that.
My bike does have an E type mech (I think) with the bracket removed and fits directly to the frame, so it might mean a double specific mech but hoped the shifter option might solve that issue. I thought with the shifter changing to a double option that I won’t have to adjust the mech stops at all.

You have a direct mount mech, which need to be double specific. A triple mech will mount too high, and you will have issues with chain retention as the diameter of the mech cage won’t match the middle ring. Direct mount mechs are themselves chainring specific. You get a M785 for example and it’ll match a 38 or a 40t ring dependent on whether you mount it slid up on the mounting bracket,for 40T, or low for a 38. The bashguard you get will match the middle ring for size, not replace the full diameter of the outer ring. You may be able run a triple as a double but you risk all sorts of problems and it’ll look awful.

I didn’t think I could change the height of the front mech as it screws directly to the frame(Canyon Nerve XC).
Does altering the shifter to the double setting mean it will default to the outer and middle rings rather than what I want which is middle and granny?
I’m not changing the middle ring so the mech will be right for what rings(32 and 24)are already fitted. Will it foul on the bash?

No, you’d limit it to not shift past the middle ring. It may work. Here’s what the double looks like,on a Nerve AM frame:


See how the mech cage exactly fits the diameter of the larger ring.

Cheers for that and the pics, I had a 2012 XT double set up on my hardtail but that was a conventional front mech and double specific 40,28t chainset.
Really don’t want to have to buy a new chainset and as you’ve said it would look horrendous just removing the big ring.
I think it will work but might have to end up either getting a double front mech or adjusting the limit screws to stop it fouling on the bash.

It should be a piece of pee. You can keep both mechs and the bashguard is a simple swap for the large chainring. Shimano can be a pain for the previously mentioned reasons, but in the worst case scenario all you need to do is file the guard a little, but it’s unlikely that you’ll need to do this.

You’ll probably need to lose a few links in the chain too, to ensure that your drivetrain doesn’t clatter unduly as the chain will be a fair amount slacker than before.

Righty, front mechs:

All you need to do is to take the crank off and change up so that the front mech is in position for the largest chainring. Find the two crosshead bolts on the top which adjust the mech’s higher and lower limit threshold and locate the “H” bolt. Now wind the screw out so that the mech appears to slowly move inward. Once you refit the crank, you can fine tune this, but you’re setting the limiter so that the mech won’t be able to move the chain further than the middle ring.

This step is optional – for ages I just remembered not to change up twice somehow, but it’s worth doing all the same. My AM bike is set up this way. You’ll still have access to the granny and middle ring as before.

Unsolicited advice bit:

FWIW, I’d fit a chain guide of some sort – it’d be a shame to waste those lovely ISCG mounts and also size up on the big ring to a 34T or 36T. You don’t need a dual ring chain device, but it’ll quieten down your drivetrain and will keep the chain in place in the bumpy stuff. It needn’t be expensive, a Blackspire Stinger is extremely good and can be had for under twenty sniffs if you shop around.

I have a similar XT set up on my hardtail and switched from a triple to a double. I can still use the same shifter but I had to change the (direct mount) front mech to double specific.

Kept the long-cage rear mech and it’s fine.