The rear mech has been produced to handle a cassette of up to 28T whereas the Dura-Ace Di2 reaches 27T, this in itself will help with marketing appeal.
Carried from the Dura-Ace is the automatic circuit breaker, preventing ‘meltdown’ in the electronics due to a crash, a feature very welcome as replacement costs are high.
Lack of a carbon cage increases the Ultegra Di2 weight to 250g, at only 25g heavier than the Dura-Ace its certainly not a problem.
