Well I finally took the plunge and fitted a Sram PG 1170 11 speed 11-36 T cassette and new chain to my road bike yesterday . Running on Ultegra Di2 RD 6870 .
I took it for a test ride and it works really well . The only "issue" it has is that it rumbles a little bit when back pedaling in the 36 T cog , but I would never normally do this anyway .
I tried B screw adjustment but it doesn't make any difference . Even putting a longer B screw in backwards as some of the on line help forums say doesn't do anything, so I'll live with it . It's really good up 15% +
Hi Benny , I'm not an expert but I find that with the 36T it allows my 73 year old legs to climb, sitting down, spinning up 10% 15% + climbs , whereas most of the guys I ride with are standing up , burning themselves out by the time they get to the top pushing higher gearing . It's not quick but I can go all day. Yes it's an effort thing.
Where did you bay your components from?
Hi Luigi , it was about 2 years ago that I bought this , from the USA . Still working perfectly .
You may also need one of these (below) to extend your derailleur hanger . I bought a Wolftooth derailleur hanger extender , used it for a while , but found it was not necessary, so made adjustments to the B screw and took it off .
Good luck !