Review: Shimano Dura-Ace Di2 9150
Aug 31, 2020
article & images by Nick Salazar
In describing the components of Di2, it's helpful to think of them both in terms of their function as a standard groupset, but also to think of how they compare to other electronic groups. As a general overview, we find that Shimano's electronic system uses just one battery, compared to the three or four (or more) batteries used by SRAM's wireless system and Vision's ridiculous "Double Wireless" system. Compared to the SRAM group, you trade the one-time inconvenience of fishing wires through your frame, in exchange for a lifetime of battery convenience, never having to swap out batteries or carry spares on your bike. Just charge once every few hundred miles and you're good to go. On the down side, there is no 1x option here as there is with the new SRAM AXS groups. However, Shimano is really throwing down a gauntlet with Synchro shifting (we'll get to that in a minute) to say that 1x is unnecessary. So, every Di2 TT system you buy will come with a front derailleur, rear derailleur, and two chainrings.
At the heart of any component are those derailleurs, plus the cranks and cassette. That's where all the magic happens. And Shimano's kit has been, for many years, the gold standard. It functions flawlessly, carrying on Shimano's tradition of unflinching, unfailing performance. Of the three major brands (Shimano, SRAM, and Campagnolo), it's Shimano's groups that are usually considered the absolute workhorses. If you need a simple installation, no-nonsense group, Shimano is usually where you want to go. And 9150 is no exception. It's truly a plug-and-play system.
The aesthetic styling of the group is striking, and somewhat polarizing. There are harder angles throughout, most noticeable on the rear derailleur pulley cage. The four-bolt crankset design continues from Dura-Ace 9000, and while I love the look, there will be others who don't. However, that crank is decidedly not aero in shape. If you don't have any qualms about using a third-party crank (and I don't), you can make some aero gains by switching to something like the glorious Vision Metron. That's one place SRAM wins out; their AXS aero crank is quite beautiful. And the Dura-Ace cassette, while not as sexy as the glorious hollow affair seen in SRAM RED, is nonetheless perfectly functional and elegant.
The front end of this TT group is where the real magic has happened in terms of both hardware and software. There is now just one button on each shifter instead of two. And you can configure them in many ways, but the default (and my preference) is that your right hand buttons shift into a harder gear, while your left hand buttons shift into an easier one. The hardware itself is stripped down from previous versions, more compact, aero, and ergonomic than before. This is especially true of the extension shifters, which used to be very long straight pods that tended to obviate any ergo shaping in your extensions. The new plugs are much shorter, allowing more of your hand to grip the extension while still keeping your finger on the shifter button. They're much like SRAM's clics in that way, which is a big plus.
And that bring us to Synchro shifting, which deserves its own page.