Originally Posted by
lortman
As you know, the Di2 road shifters won't shift a MTB rear derailleur.
They will shift MTB derailleurs but you can't mix MTB and road derailleurs. So you would need to use a MTB front derailleur which can take max 50 to 52 tooth chainring, according to another recent thread.
We have 3 tandem triples that shift flawlessly. I get the best front shifting using matched Shimano chainring sets. A waxed chain slows the rear shifting. The front derailleur should be matched to the size of chainrings.
We have a bike with 26/36/48 chainrings using a DaVinci crankset. This should work with XTR Di2 and road shifters. It currently shifts smoothly using a fd-6503.
If you want to go to 11 speed I think you can put a 11 speed MTB cassette on your 9/10 speed rear wheel. Someone correct me if I'm wrong.