Quote Originally Posted by fortyfour View Post
What you need to know is this: When Shimano introduced "Dyna-sis" shifting in their mountain bike shifters/derailleurs, they changed how much cable is pulled per click. So road and mountain Shimano are no longer compatible. 10 speed or 11 speed. None of it is compatible. You need to stay within the groups and allocated speeds. The only caveat is that you can possibly run a 10 speed mountain cassette with a 10 speed road group. But the caveat to that is that it depends on what the low end of the cassette is. A long cage Ultegra rear derailleur does not work with a 36t cassette FYI. The rear derailleur pulleys slam into the last cog and no amount of b-tension will get it out of the way. Shimano does not make a 34t cassette either (or at least not that I saw via my OE account). Their cassettes go up to 32t in road, then 36t in 10spd mountain and 40 or 42t in 11 speed mountain. This is why I had to use mixed components and deploy that Jtek Shiftmate.

Shimano Di2 is a different story so long as you keep road front &rear derailleurs or mountain front & rear derailleurs - the shifters don't care. You can't mix and match that stuff though from what I understand: So you'd have to have a pair of road hooded shifters with a set of XTR front and rear derailleurs.
Shimano makes an XT 10sp 11-34 (CS-M771). 10sp Shimano road levers shift a 9sp Shimano MTB rear derailleur across this cassette perfectly-- I have 5700 shifters pushing a 9sp Deore XT (M750) on this cassette on my NFE currently, no Jtek needed. Cheers.