Streamlined, powerful, and slimmed down in all respects, the Ultegra FD-R8150 Front Derailleur cannot be equated physically with the previous model. The design almost appears to be more like the R8000 mechanical version, yet while tipping the scales at about 114 grams, the new design shifts 45% quicker than Shimano's FD-R9150, which was already the benchmark for the fastest front derailleur on the market. Speaking of efficiency the frontal area of the FD-R9250 has also reduced by 33% to decrease aerodynamic drag, a point of emphasis for those who measure watt savings in podium steps but more of a visual beauty for mere cycling mortals. The R8150 model is only available in a braze-on type design, and if you require a clamp, you must use the specified Shimano SM-AD91 model in the proper round tube size.

In the R8150 Di2 set-up the shifter levers, which require a very low power requirement, employ a secure wireless communication system are amply powered via a coin cell battery in each shifter body. The front and rear derailleurs handle the motors and actual shifting action and they are still powered by a new cylindrical internal seatpost battery (BT-DN300) which features three wiring ports for the SD300 e-Tube wires. Shimano rates the battery level at about 2000km of use, meaning you rarely have to charge the battery, which is much more powerful. As such, each derailleur has it's own wire that goes directly to the battery. Why is there a third wire port on the BT-DN300? Well, Shimano allows you wire the shifters in as well if you choose, but with so many cockpit set-ups now requiring a fully internal routing into the fork from the bar-stem, and down into the frame, the wireless option is the simplest and least challenging way to set-up your R8150 Di2 system. Also, by moving the charging and control access to the R8150 rear derailleur, Shimano also delivers easier adjustment, a more stable charging connection, and overall simplicity that current Di2 users will deeply appreciate.

Functionally speaking, the FD-R8150 has been optimized for three chainring combinations: 54-40, 52-36, and 50-34, with the 16T difference of the latter two options the max allowed by the derailleur guide cage shape. It does accommodate a 54T large ring for TT set-ups though there is not an Ultegra crankset sold in that combination. As with all Ultegra components, the materials have been selected for the best combination of reliability, functionality, weight, and durability. Four link bushings ensure fluid, reliable movement over thousands of shifts, while aluminum is shaped and utilized for the clamp, body, and outer link plate. The inner plate is made with steel for optimal durability and strength. While moderately light and incredibly efficient, Ultegra components are widely considered the longest lasting options on the market. From the Di2 side of things, the FD-8150 features a sealed composite housing with a single SD300 e-Tube wiring port and the internal servo motor and electronics, which are all highly resistant to water, muck, and grime. All necessary Di2 alignment adjustments are made via the Function button on the rear derailleur.

Along with the release of the 12-Speed series components, Shimano also created their new generation E-Tube Project app which truly simplifies the set-up, shift button customization, battery level check, and diagnostic process, with a much more effective user interface for iOS and Android devices via the system's Bluetooth Low Energy communication channel. While an upgraded e-Tube PC site is still an option, most users find the app to be the easiest option available.