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First Ride: Shimano Dura-Ace Di2 Hydro

Dan Cavallari checks out the new Dura-Ace groupset and come away impressed with what he sees.

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CALPE, Spain (VN) — While the new aesthetics of Shimano’s updated Dura-Ace Di2 (R9150) groupset indicate wholesale change, the overall experience is one of refinement.

Dura-Ace Di2 offers some of the crispest shifting on the market as it did before, adding subtle tweaks like new shift options and controls. It’s the hydraulic brakes, however, that seem to have made leaps and bounds over previous Shimano road offerings. A more positive braking feel and more adjustability are enough to make the new group worth a second look. Couple that with the new power meter and Dura-Ace R9170 — the hydraulic version of the new Di2 system — becomes an intriguing purchase.

If you’ve ridden Dura-Ace 9070 Di2, you won’t notice much difference in shifting performance, and that’s a good thing. When you start with the smoothest shifting, it’s ideal to end your refinement with the smoothest shifting. Shimano has done that. Small finger movements against the paddles lead to quick, clean shifts every time. Shimano refined the shape of the hoods on the hydraulic group too, so the sensory experience is almost identical to riding the hoods of the mechanical group.

The derailleurs remain a wired system despite the arrival of wireless shifting from SRAM and FSA. “We didn’t think wireless changes the ride experience,” said David Lawrence, Shimano’s road and pavement product manager for North America. “Our system is robust and reliable. When we can add functionality via wireless, we will. We are already wireless, so down the road we could pursue that. We also think there’s simplicity with a single battery.”


Some of the drivetrain changes are so small you might not notice them at all. The inner chainring on the crankset has moved slightly inboard to better accommodate cross-chaining. Aside from the addition of an 11-30 cassette, the gears out back remain unchanged. But some of the small changes you will notice. The brake hoods on the hydraulic Di2 system are much smaller than previous iterations and closely match the shape and feel of the mechanical brake hoods. The two buttons hidden under the top of the brake hoods aren’t new, but they have some added functionality: Before, you could control your computer with them. Now, you can control your computer or set those buttons up to shift one of your derailleurs.

And while your old junction box will continue to work with the new Di2, Shimano has added a cleverly hidden handlebar plug junction box that makes for clean routing within your handlebar and easy access to the junction box buttons.

Bar end plug junction box. Photo: Dan Cavallari |
Bar end plug junction box. Photo: Dan Cavallari |

Sprint shifter buttons won’t change, but the climbing shifters are different. There are two individual buttons rather than the blocky, two-button design we’ve seen before. This creates a sleeker look and more options for positioning.

So nothing too mind-bending in terms of changes, just a sleeker system that quietly adds to the user experience. Why buy it, then? The bigger changes to the system focus on automation and braking. You’ll be in familiar shifting territory right up until you start digging deeper into the system: Shimano now offers Syncro Shift in three flavors. You can do semi-Synchro, full-Synchro, or a custom Synchro programmed within the E-Tube app.

The Shadow-style rear derailleur takes its cues from Shimano's XTR mountain bike rear derailleur. Photo: Dan Cavallari | VeloNews
The Shadow-style rear derailleur takes its cues from Shimano’s XTR mountain bike rear derailleur. Photo: Dan Cavallari | VeloNews

The semi-Synchro option shifts your rear derailleur to help keep your cadence a bit smoother when you shift your front derailleur. If you shift from the small ring to the big ring, for example, the rear derailleur will shift automatically two gears down into a lower gear. The full-Synchro option shifts both derailleurs automatically, depending on whether you want a harder pedaling experience or an easier one.

You can change from full-manual shifting into semi-Synchro and full-Synchro modes by double-tapping the junction box button. To get your battery life, hold down the button. Continue holding to see which shifting mode you’re in.

Given the intended audience of a top-of-the-line groupset like this, I wonder if the semi-syncro and full-synchro options are really necessary. Shifting may be complicated for newbies and once-a-year hobbyists, but veteran riders — the riders who are likely buying Dura-Ace-equipped bikes — will have no problem. Personally, I found the Synchro modes to be more annoying than functional, especially when cresting a climb and popping up into the big ring to continue acceleration. If I was paying attention, I could anticipate those Synchro shifts and essentially counteract them quickly to maintain acceleration, but I don’t want to have to pay attention. I want to react. I’m sure it just takes time to get used to this feature.

Still, the Synchro system works as intended, and smoothly in most situations. It might make sense for new riders or those who lack the confidence to shift correctly when necessary, but those people are very likely more at the Shimano 105 groupset price point.

All this customization can be controlled in Shimano’s E-Tube app. Full OEM tinkering and setup still requires the PC version, but there’s also a tablet version that can interface with the group wirelessly. Consumers will also be able to easily configure the system with a new phone app that’s more limited than the other versions, but still offers enough customization to get more than just the basics accomplished. You can set up the Synchro settings, assign new shifting profiles, and set up the hood buttons for shifting or computer control.


The most exciting improvements aren’t meant to make you faster. Quite the opposite: The hydraulic disc brakes ended up being everything I hoped they would be. If you’ve ridden other Shimano road disc brakes, you know that one of the major complaints was an inconsistent and sometimes soft lever feel. Shimano heard your complaints.

The system has improved from top to bottom, starting with the rotors. Those large fins are intended to aid in cooling — up to 86 degrees Fahrenheit cooler, according to Shimano — which should help provide a more consistent braking feel on sustained descents. The rotors are offered in 160mm and 140mm options and are UCI-legal.

The flat-mount caliper and finned rotor. Photo: Dan Cavallari |
The flat-mount caliper and finned rotor. Photo: Dan Cavallari |

The calipers aren’t dramatically different from previous road calipers we’ve seen from Shimano, but they are Dura-Ace branded and are supposedly lighter than their predecessors. More changes happened at the other end of the system. The levers offer a reach adjustment as well as a Free Stroke adjustment. The former adjusts how far away from the bars your levers sit. The latter is intended to adjust the lever’s contact point, a major frustration with previous road disc levers. While there doesn’t seem to be a ton of adjustability here, there’s enough to ensure your left and right levers are close to consistent with each other.

The bleed port on the lever has been relocated so you won’t have to pull the brake hoods off the top of the lever body. The port is instead closer to the handlebars, which is much more convenient and avoids any deformation of the hood cover itself. The bleeding process is straightforward and not much different from any other hydraulic brake system I’ve seen. It bleeds bottom to top using Shimano’s existing bleed kit. You’ll need a new bleed fitting though (another small part to get lost in the toolbox. Yay.)

Watt’s that?

The Dura-Ace power meter is perhaps the most anticipated addition to the group. It doesn’t break any new ground in power meter technology, but it appears to be smartly conceived and well executed in terms of hardware.

I don’t have any data to speak to the power meter’s accuracy or consistency after only two days on it. That will have to wait until I get a unit into the office to test long-term, but even without hard data, there’s reason to be excited: a well-sealed and hard-wired system with a single battery, easy install, and left and right power sums up a lot of what I want from a power meter. You’ll need a new tool to install the non-drive crankarm (the little plastic tool we all have kicking around won’t work because there’s an electronic connection in the spindle), and it is included with the crankset.

Shimano says the rechargeable battery should get about 300 hours per full charge. The charger has a magnetic fitting that attaches to the power meter on the drive side. That means no watch batteries to contend with, though of course your data is subject to battery freshness as is the case with any power meter. Shimano says you should be able to get up to 1000 charges on a single battery, which is fortunate because the battery is not replaceable. If it dies, you’ll need to get a new crankset.

Since everything is neatly sealed (the battery lives in the spindle between the two crank arms), the power meter should be weatherproof too.

There are strain gauges on both sides, so you get left-right power readings that Shimano says should be accurate within +/-2 percent. Shimano claims that since the system is hard-wired, the data should be as accurate as possible.

While many current power meters use accelerometers, Shimano has instead stuck with a magnet that attaches to the bottom bracket shell. This supposedly helps with accuracy, but it can be a bit of a pain to install. Luckily, Shimano includes a handy tool to help you position the magnet correctly.

The system costs $1,550 including chainrings.

The ride

I spent two days on the climbs in and around Calpe, Spain and came away impressed but not blown away. I was admittedly unenthusiastic about Synchro shifting, and while I liked it more than I thought I would, I don’t see myself using this feature very much. You’re essentially learning a new way to shift, and I’m not sure this new shifting technique addresses a problem that really exists. I had the same reaction while riding Campagnolo Super Record EPS set up with automatic shifts. It seems similar to those semi-shifting options in cars: I want to drive manual, but I don’t want to push the clutch. Is that clutch-pushing really a difficult thing to catch onto?

It will be interesting to see if this function really catches on with consumers, as I’m sure there are riders out there who will benefit from it.

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That said, the shifting is crisp every single time. That’s what I’m really after, and as someone with generally small hands, I appreciate the easy reach and super-short throw of the Di2 paddles. The streamlined hood design is so good that it was easy to forget I was on a hydro lever at all. There’s almost no extra bulk, which is quite a feat.

I’m a big fan of the hood buttons that can be used for shifting. It’s a convenient spot and requires a very small hand movement. You can only control one of your derailleurs with the two buttons, but if you go into full-Synchro mode, you can essentially get all the shifting you need from two buttons. (Is this perhaps the best reason to set up a Synchro shift profile?) If you’re not into that, you can set those buttons to control your computer, or even your ANT+ enabled lights.

While I’m excited to spend more time on the power meter, I was far more excited about the hydraulic disc brakes and came away feeling Shimano had made some real gains here. The lever feel is night-and-day better than any other Shimano levers I’ve ridden. While I would like a bit more adjustability, overall the system seems to meet the high bar we’ve all set in our minds for anything labeled Dura-Ace.

Not everything was a home run, though. As a Shimano mechanic walked us through the system setup, I felt a bit overwhelmed by all the bits and pieces. As a former mechanic with 14 years of experience, if I’m feeling overwhelmed, what chance does the home mechanic have? These are perhaps the sacrifices we make in the name of exceptionality, but when SRAM created an exceptional system that installed in mere minutes, that should have been Shimano’s call to match or exceed that level of usability.

There was only one step backward in the group as far as I could tell: the climbing buttons. While the old climbing buttons were bulky and certainly unattractive, I’m not sure the new two-lever design will be any better, and now instead of one bulky unit on your bars, you’ve got two. This could use some streamlining.


Ultimately, Shimano did justice to the Dura-Ace name: Aesthetics are spot-on, it’s a versatile system, the brakes are a vast improvement, and the power meter is a smart addition to the family. The venerable Japanese company is perhaps guilty of adding bells and whistles where none are needed, and I’m of the mind that Synchro shift solves a problem that doesn’t exist for such high-end customers, but the group doesn’t suffer for it. The new group is worthy of the Dura-Ace name.