I've gone for a 2×9 (granny and 36T middle) for a change and have been adjusting the [XT] front mech to suit using the Shimano instructions for a triple.
I'm finding that the chain, that has been shortened by about 3 links) is either a bit prone to falling off the middle ring when changing up from the granny, or a bit difficult to get onto the middle. Are there any tricks to setting this up or will I need to get a bash or a double specific front mech?

I had it working ok with a triple mech (24/36) but still had the chain jump off a fair bit because I couldn't close the gap to the middle ring teeth because it fouled the rear swingarm (full susser) and also rubbed on the granny ring if I did. I changed to an SLX double and it's been perfect since.

just set it up as a normal triple, but use your limit screws to stop the mach going past the middle ring. also, what teeth granny are you using? unless your using the SLX double, it wont work more than a 12 tooth jump……hence why its falling beacuse there is not enough throw.

It's supposed to be a SLX 36t (triple I think) BUT I think CR sent me an LX – at least that's what it says on the backing card and it doesn't look like an SLX (black and silver with holes in each tooth).
What does the '12 tooth jump' mean? – the minimum it can shift is after 12 teeth?

The mech needs to be in the same position as if you were using a triple. You will see all the profile bits on the cage are there to push the chain and then provide clearance. So the mech will now look stupidly high up the seat tube. I found it difficult to stop it throwing the chain over the middle ring when changing up, so I fitted a bash ring and it works fine.

it means if you have a 36t middle, the smallest granny you can have is a 24t. if you have the standard 22t, then a 36th wont work that well as its a 14 tooth jump between sizes…….

got ya, thanks Trev. 🙁

I had exactly the same problems as you when using a triple mech on a double setup. I had moved the mech downwards, but it actually needs to sit in the same place as on a 3 ring setup (As bigjohn said). After moving it back to its original position it worked fine. Having said that, I now use an SLX double mech which is way smoother!!

Nearly gave up on the idea (and have even bought another 'normal' middle ring to replace the 36T just in case) but I think I'll stick with it.
Cheers guys.

Manchester Trev – Member

it means if you have a 36t middle, the smallest granny you can have is a 24t. if you have the standard 22t, then a 36th wont work that well as its a 14 tooth jump between sizes….

Two of my bikes have standard mechs and 22/36 chainrings. Mech is just set up as normal for a triple and the limit screws wound in to stop it going over the 36. It just works. It will only shift cleanly from the granny to the36 from granny 1-5. From 6-9 it tends to overshift

It can be made to work right as I had a triple front mech running 22/36/no bash but it took quite a bit of fiddling to stop it throwing the chain off on upshifts. Then I changed to an SLX double mech and it just shifts a million times better and is a doddle to set up…and looks better as it sits down nearer the rings than you have to run a triple mech.

i didnt say it wouldnt work, only that it doesnt work as well.

Ive got a double and bash, Ive set it up on a double click, otherwise it was rubbing a bit little to little, big to big.