I am planning a MTB with Di2 build, but already have a Road bike Di2 set up so I want to keep cost to a minimum.
My question is will Di2 work with a Di2 RD and a double crankset/mechanical FD or will it just confuse the RD when mechanically shifting on the FD?
More specifically I was thinking of ordering a 10 speed XT groupset with a double crankset and fitting a Di2 rear mech, internal loom, handlebar set and a Di2 drop handle bar switch. http://www.fawkes-cycles.co.uk/19146/pr ... -hand.aspx
To keep the cost down even further I would use an 800maH Lipo stick battery and mount it in the seat post as in my road set up (9 months on and still not charged).
Is this even feasible or will I need to keep it to one chainring or take the more expensive option and add a Di2 FD?