Yes – thats how you convert a triple to a double. Don’t need to change chainline or anything, maybe just put a bash where the big ring used to be if you’re in the habit of going over logs/rocks. Will also need to dial in stop screw of FD to prevent shifting off the middle, and maybe shorten chain a little.

If you have the big ring in the middle position you can use the whole block in the big ring and just use the granny as a bail out option.

You will need shorter chainring bolts if you don’t fit a bash ring.

I have a double that is simply a triple with the big ring taken off and the chainring bolts replaced with narrow ones. Works spot on.

The ‘handicap’ with a triple converted to a double is that it looks less neat. There’s no real functional difference.

The handicaps of a triple are weight and gear duplication.

A true double will position the rings perfectly symmetrically, so it is still not good practice to cross-chain despite the manufacturers playing this down (and wanting to sell chains).

If you start with a triple, I would just remove the large ring and leave the chainline alone. If you fit a bashguard, expect it to rub if you run granny with the small 2 sprockets or the large/middle with the smallest sprocket unless you space it outboard with washers.

Adjusting the front mech to remove the outer position on the shifter is correctly described above.

Go one, try it. Worst case is you have to revert back, or it all explodes (unlikely, more a poor joke from me).

PaulD

Interestingly, the two rings on the SLX M665 double are in exacltly the same place as the middle & small rings on the SLX M660 triple, so in this case Shimano didn’t bother adjusting the chainline for the double. Don’t know what they’ve done with the new ten speed XT doubles?

Yeah, I know but TBH I figured that since it’s typically not a massive difference, I didn’t reckon the OP would really care or notice that 🙂