Originally Posted by
trdsupragt
I think brake cable pull ratio is still pretty much the same.
As far as shift though, definitely different. And I think even if he wanted to change the rear the 11, and leave the front as is, it wouldn't work out so well because of the narrower 11s chain and the wider 9s FD cage. You could probably get it to shift, but it would likely be at the extremes of what the FD could do. Not to mention 11s FD's have that stupid plastic bumper on them now too (thanks a lot Shimano).
Brake cable pull for all Shimano brifters using shift cables routed under the bar tape is different than for brifters having exposed shift cables. Shimano also changed cable pull ratio for 11 speed shifters and derailleurs so that the newer shifters will not work with either the front or the rear derailleurs from the older style groups. Added to that, the 11 speed cassettes require a cassette body that is almost 2 mm longer than the cassette bodies used for 8,9, or 10 speed cassettes. Upgrading from 8 or 9 speed to 11 speed is pretty much an all or nothing proposition
Dura Ace 7900, Ultegra 6700, and 105 5700 brake calipers are compatible with 11 speed brake levers but using the older Dara Ace 6800, Ultegra 6600 or 105 5600 brake callipers from previous generation 10 speed groups will result in a noticeable increase in the effort required to stop your bike, so upgrading from 10 to 11 speed could also be and all or nothing proposition