Upgrading Ultegra di2 6770 to 11 speed questions.
I'm planning to upgrade my 6770 to 11 speed and I have a couple of questions. I've read that when upgrading that both derailleurs need to be upgraded unless the firmware is old. Since I have never upgraded my firmware (built the bike in 2013) does that mean that I can just upgrade the rear derailleur or am I just dreaming?
If I do have to upgrade both derailleurs can I mix a 6870 front with a 9070 rear?
Oh, the reason I'm upgrading to 11 speed is because I am old and fat and I want to go to a larger rear gear than the 28 that I have now. I know, I should htfu but whatever.
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I may be fat but I'm slow enough to make up for it.