Shimano's new 11-speed Dura-Ace Di2 RD-R9150 rear derailleur boasts a sleek profile , which is practically hidden from the wind and, finally, brings synchronized gear shifting to the road honed in the XTR Di2 system Off-road oriented. Enabling synchronized gear shifting allows the Di2 system to work its magic automatically moving your chain from gear to gear without your input and intelligently managing the fleet of gears at the rear of your drivetrain. However, this is not a requirement for use so the traditionalists among us will breathe a sigh of relief upon learning that this switch also provides the same precision manually controlled and customizable gear shifting which we have come to expect from Di2.

By combining the rear and front derailleurs with each other Synchronized Shift can actually calculate your efficiency and perform simultaneous forward and reverse shifting to eliminate cross-shifting and set you up with the best chain line for any given gear. These shift patterns depend on the direction you shift in and from the combination you switch and can also be programmed using Shimano's E-Tube system so you can set your preferences in advance to guarantee that your internal transmission is not working. I'm not plotting against you.

The gear shift itself is incomparable, since the shifter always knows where is it located therefore its stroke is not limited or lengthened by imperfect cables. It places the chain directly on each gear and jumps between those positions with amazing speed. Like other Shimano Di2 bits Dura-Ace rear derailleur compatible with Shimano E-Tube wiring system resistant to rust, stretching freezing and generally reliable. Its modularity allows it to be easily installed on almost any frame although it operates with less friction if the frame is built with Di2 in mind.