I currently run an Ultegra 6870 Di2 mechanical disc brake system, with the older external battery. I have post mount frame with a flat mount fork (currently with a converter to PM). I wish to upgrade the brakes to hydraulic. I've seen the DA R9170 shifters for a good price - close enough to the new Ultegra ones to go for them instead. So now my questions.
1) I plan to use a flat mount brake on the front (I already have a suitable caliper) but will the levers also work with a post mount caliper on the rear?
2) Will the shifters perform a basic up and down shift without firmware upgrades and/or battery replacement? I'm not concerned by the additional semi sync shifting, hood buttons, BT etc for now.
3) Anyone want to buy 6870 Di2 shifters and TRP Hy/Rd calipers?
(I may keep the calipers for another bike).
Thanks in advance,