I have some very hilly riding coming up and was wondering if the 12-30t cassette will work with Ultegra Di2? I think I read somewhere that the maximum was 28 teeth but is that Shimano being conservative?

Thanks

I've used the Ultegra Di2 rear derailleur with a 12-32 before, with zero issues...

I've also setup Ultegra Di2 with an 11-32 cassette without an issue. It depends on the precise geometry of your dropout and the chain length, but with a 30-tooth cog it will probably work fine on most bikes, and on some you'll get away with a 32. Also remember that you can switch the inner ring on a compact for a 33-tooth (not available from Shimano, but is available from Stronglight or TA).

Thanks for the replies. I have one of these:

http://www.bmc-racing.com/int-en/bikes/2012/road/model/roadracer/sl01/sl01_ultegra_di2.html

I noticed that the '13 plain Ultegra model has the 12-30t cassette:

http://www.bmc-racing.com/int-en/bikes/2013/road/model/roadracer/sl01/ultegra_.html

I don't believe the frames have changed from the '12 to '13 model. Presumably that will work then?