Shimano calls the R9200 series the "Science of Speed", as every detail, every decision, and every component of the R9200 series is engineered to deliver a faster, more reliable, and more intuitive ride experience. Shimano dedicated years of research, development, and testing to refine this flagship road system and the RD-R9250 Rear Derailleur features prominently in terms of performance, capability, and actually replaces the Junction A box system of the previous versions. At 215 grams (listed), it is also lightweight and houses the new charging port, LED indicator, D-Fly communication system, and Function button. As with all Dura-Ace components, the materials have been selected for the best combination of quality, functionality, weight, and durability. This R9250 Di2 shifting system delivers 58% faster rear shifting compared to the R9100 Di2 and while some may point out that Shimano continued with a partially wired system over full wireless, the engineering rationale has been strong and sound.

In the R9250 Di2 set-up the shifter levers, which have a very low power requirement, employ a secure wireless communication system that is 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 R9250 Di2 system. By moving the charging and control access to the rear derailleur, Shimano also delivers easier adjustment, a more stable charging connection, and overall simplicity that Di2 users will deeply appreciate.

Now built in a single cage length model that can handle 12-speed Hyperglide+ road cassettes in the 11-28, 11-30, and 11-34 cog options, the R9250 ensures road cyclists can meet their higher cadence pedaling styles and overall gearing range requirements in conjunction with chaining pairing. The 11T composite Guide and Tension pulleys spin smooth and fast, while offering serious longevity and chain engagement. These ride in a strong and resilient cage, with both plates in CFRP composite that has been well-proven on the road to deflect torsion and allows for a specific shaping that is much harder to create in alloy materials. Stainless steel hardware, anodized aluminum B-axles, and four flouric coated link bushings keep the alloy and composite body construction functioning and moving with precision and fluidity for thousands of miles of premium performance.

Along with the release of the R9200-series components, Shimano also created their 4th generation E-Tube 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.