With the advent of the XT Di2 RD-M8050 Rear Derailleur, Shimano's Di2 has finally come to Deore XT, which may be the most popular drivetrain model in the world. The XT version is built for more aggressive terrain, features a much friendlier price point, and actually represents an upgrade on XTR in some ways. One of the biggest changes to XT's version of Di2 is that it now wirelessly connects to Shimano's E-Tube platform via Bluetooth. That means that you can initially set your drivetrain up at home with a computer or tablet and then make targeted adjustments using your smartphone while you're on the actual trail. The shifting itself is peerless, as the derailleur always knows where it is, so its travel isn't restricted or lengthened by imperfect cables. It situates the chain squarely on every cog and it jumps between those positions with startling speed. No hesitation, no grinding. Ever. And since Shimano builds the XT Di2 derailleur with a motor that's twice as powerful as its road counterparts, it'll always have the extra oomph necessary to maintain seamless, accurate shifting even when inhibited by a healthy accumulation trail muck.