Shimano has been hard at work refining their highly reliable and successful Ultegra Di2 group. Similar to the Dura-Ace RD-R9150, the RD-R8050 features Shimano's Shadow low profile design. The Shadow design sits much closer to the frame and tucks the derailleur in and under the cassette. This protects the cage from ground contact, while improving the accuracy and clarity of shifting. By bring the derailleur closer to the cassette it creates far quicker and cleaner action. The RD-8050 features a shorter throw that results in quicker, more precise shifts with less effort, even over the wider spread of the 11-32 and 11-34 cassette options.

Shimano offers the 8050 derailleur in two versions; the SS version that works with up to a 30T cog and a medium cage GS version that works up to a 34T cog. The GS version can also be used with Dura-Ace Di2 to use a 32T or 34T cog with a Dura-Ace group (there is no 9150 GS rear derailleur).

Most derailleurs use a spring and cable tension to move the chain from cog to cog. With the advent of Di2, the RD-R8050 Di2 rear derailleur employs highly innovative digital technology where an electronic signal is sent to a worm drive motor move the chain from gear to gear. Shifts are lightning-quick with no hesitation. For those concerned with damaging the derailleur in a crash, Shimano's engineers included a servo-saving mechanism that allows the rear derailleur to handle a big side impact with minimal damage. Shifting is completely customizable. Shifting speed and the amount of cogs shifted with a press and hold can be tuned to each rider's preferences.