Shimano Dura-Ace Di2 RD-9070 Rear Derailleur $699.95
It's hard to believe that electronic shifting has been in our vocabulary, let alone on our bikes, for less than half a decade. And while electronic perfection has now become the en-vogue aspiration point for engineers, it's easy to forget that Shimano got the bandwagon kick-started. We still remember the dropped jaws and even the skeptical and naysayers at the advent of 7970. We understood: it was relatively unproven technology. But now, we've already witnessed the unbranded prototype power of the Dura-Ace Di2 RD-9070 Rear Derailleur under the legs of pro teams throughout the 2012 season. Accordingly, we hold no reservation in saying that 9070 is perfection perfected.
Starting at the question that's on the tip of everyone's tongue, is it lighter than 7970? The answer is yes, but only by around eight grams. However, if you're like us, 9070's enhanced shift precision is more important than comparing lightweight to lighter weight. But, as long as we're making comparisons, you'll immediately notice that 9070 is far more compact than 7970, and the cable routing is simplified and cleaner. In fact, Shimano based the shape and connection points in tow with the Ultegra 6770 rear derailleur. And along these lines, we find that the relatively confusing setup and wire cluster of 7970 has been replaced with Shimano's newest generation of its E-Tube electronics system.
Now, with your PC computer, you're able to make rear derailleur adjustments and setting alterations without even picking up a wrench. So, while you're manually rotating the cranks, E-Tube allows you to direct and adjust the guide pulley up or down, as well as to shift the gears up or down the cassette. You can even program the number of gears that you're running, a vital application given that 9070 operates with both 10- and 11-speed cassettes. Of course, E-Tube also performs a complete system and problem diagnosis, pinpointing any possible human error as a result of improper setup or riding. This removes the slightest hint of shifting inaccuracy, essentially keeping your shifting system running on-point at all times, even if you don't possess a fiber mechanical aptitude.
Extending this sense of power-to-the-user functionality is 9070's ability to shift up to a 28 tooth cassette capacity. Now, with 11-speeds and a high gear capacity, your available gear range will propel you through the fastest and steepest conditions that the road will throw at you. And when speeds become fearsome, and a crash unfortunately occurs, the derailleur cage will move itself out of harm's way, protecting at least one of your investments.
The Shimano Dura-Ace Di2 RD-9070 Rear Derailleur is available in one color and in one size.
Confused about how to build your Di2 Kit? Read our Learn Article.
What community has to say
Is it actually correct to state that "9070...
Is it actually correct to state that "9070 operates with both 10- and 11-speed cassettes"? Emailing Shimano directly resulted in the advice from their Technical Support team that the only way to run the new 9070 Di2 system with a 10-speed drivetrain is to use the Ui2 derailleur. RD-9070 only works with a 11-speed drivetrain. Can you confirm what's the actual situation and how, if possible, 9070 Di2 can be made to run 10-speed?