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Installing Shimano’s Di2 group

Ever since Shimano introduced the 7900 Di2 group at last fall’s Interbike show, it’s been surrounded by questions (as is any revolutionary new product). At first, the major question was simply Shimano’s wisdom in daring to venture down a path previously abandoned by Mavic and Campagnolo. Then the question was: will it pass the litmus test of adoption by professional riders and mechanics, who are historically traditional and resistant to change? Finally, will the parts ever actually become available at retail — and if so, will consumers buy?

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By Zack Vestal

Shimano Di2 Install: derailleurs and shifter/brake levers bolt to the bike almost identically to their mechanical cousins.

Shimano Di2 Install: derailleurs and shifter/brake levers bolt to the bike almost identically to their mechanical cousins.

Photo: Zack Vestal

Ever since Shimano introduced the 7900 Di2 group at last fall’s Interbike show, it’s been surrounded by questions (as is any revolutionary new product).

At first, the major question was simply Shimano’s wisdom in daring to venture down a path previously abandoned by Mavic and Campagnolo. Then the question was: will it pass the litmus test of adoption by professional riders and mechanics, who are historically traditional and resistant to change? Finally, will the parts ever actually become available at retail — and if so, will consumers buy?

But now the question most frequently asked is, “Does it actually work? And if so, how?”

The answers have been evolving this spring. In February, riders on both the Columbia-Highroad and Garmin-Slipstream teams rode bikes fitted with Di2 in the Tour of California. While not all finished the race on the groups, it showed promise that the parts were actually fit for the rigors of the pro peloton.

Further indicating more widespread acceptance, in the last few months, manufacturers have shown bikes that incorporate Di2 design features into the frames. For example, the new Scott Plasma3 TT bike, Willier Cento 1, and Giant TCR Advanced SL (to name just a few) are built with integrated Di2 wires and battery packs.

Shimano Di2 Install: A battery bracket attaches to the downtube with bottle cage braze on bolts, and zip ties.

Shimano Di2 Install: A battery bracket attaches to the downtube with bottle cage braze on bolts, and zip ties.

Photo: Zack Vestal

Finally and most telling, Di2 parts are now available at retail as individual components.

But for most, the question remains: “Does Di2 actually work? And if so, how?”

Shimano 7900 Di2, installed

Three weeks ago, VeloNews participated in the installation of a brand-new, final production Di2 group. Shimano representatives spent several hours in our tech room unboxing and installing off-the-shelf Di2 components on my 2006 Trek Madone.

The four elements of the Di2 system are the shifter/brake levers, a wire harness between the two levers, a battery pack with wire harness, and the two derailleurs.

Shimano Di2 Install: Complete on the bike frame, Di2 looks quite handsome.

Shimano Di2 Install: Complete on the bike frame, Di2 looks quite handsome.

Photo: Zack Vestal

The Di2 parts bolt on a bike in exactly the same fashion as their mechanically activated counterparts. Installation and adjustment is just as easy (or easier). The instructions are well-written and concise, and the most significant difference between Di2 and mechanical Dura-Ace 7900 is simply the attachment and routing of electrical wires rather than shifter cables and housing.

My interpretation of the installation fundamentals is as follows:

  • 1. Attach the parts to the frame, the same as with mechanical Dura Ace 7900. The shifter/brake levers bolt to the bars just like mechanical 7900 levers. The derailleurs bolt on just the same, but do not adjust limit screws by manually pushing the derailleurs across their range of motion. The height and angle of the front derailleur should be the same as its mechanical cousin, but the front mech has an additional “support bolt,” which braces the trailing edge of the derailleur body. The support bolt can be tightened such that it butts the braze-on or clamp and provides bracing support for the derailleur. Additionally, it gives a touch of angle adjustment.
  • 2. Install the battery bracket and wire harnesses. NOTE: A special tool is required to plug the wires into their terminals.
    • a. First, an upper “Y” style wire harness plugs into each one of the shift levers and joins them at a junction (called “junction A” in the service manual).
    • Shimano Di2 Install: C-channel self adhesive tape holds Di2 wires in place against the frame, and gives a super clean look.

      Shimano Di2 Install: C-channel self adhesive tape holds Di2 wires in place against the frame, and gives a super clean look.

      Photo: Zack Vestal

    • b. Mount the battery bracket using bottle cage braze-ons and zip ties.
    • c. Mount the lower wire harness, which affixes in place of the bottom bracket cable guide.
    • d. The 3 wires of the lower wire harness and battery bracket connect: 1) the upper harness to the battery bracket; 2) the rear derailleur; and 3) the front derailleur. The longest wire runs along the down tube up to the upper harness, plugging in just below the “junction A.” The other two run along frame tubes to each derailleur.
    • e. Each harness comes with self-adhesive C-channel finishing tape to secure the wires cleanly to the frame tubes.
  • 3. When all the connections are secure, the chain is installed, and the battery is charged and mounted in the bracket, the system is alive and ready to adjust. In contrast to mechanical Dura-Ace 7900, the Di2 system requires adjustment of shift position first, and limit screw adjustment last.
    • a. To adjust the rear derailleur, use the buttons on the shift lever to shift the derailleur into the midrange of the cogset. Press and hold the button on “junction A” until the red LED illuminates—the device is now in “adjustment mode.” Now, each press of the shifter button moves the derailleur .2mm in either direction, such that the guide pulley can be perfectly centered under a cog. Once this is done, press and hold the “junction A” button to exit adjustment mode, and shifting should be perfect.
    • b.After adjusting the rear shifting, adjust the limit screws. Using the Shift to the large cog, and then the small cog, and dial in the limit screws such that the derailleur can move to the cog without moving too far—then back out the limit screw by one turn. The derailleur automatically overshifts by a half step to ensure the shift is made, then readjusts itself.
    • c. The front derailleur is even easier. After ensuring that the height and angle are correct, dial the lower limit screw as normal. Then turn the cranks and use the shift buttons to shift into the big chainring. Adjust the upper limit screw as normal.

From this point, the system should be shifting almost perfectly. Within a day or two of the initial install, I found that I needed to reposition the front derailleur and micro-adjust the limit screws. Same thing with the rear derailleur — some fine-tuning was required after a day or two of easy riding to get a feel for the initial performance. But rather than turning a barrel adjuster, all I did was press and hold the “junction A” button, move the derailleur a micro-step in the direction needed, and then press the button one more time to exit adjustment mode. Once familiar with the basic principle, adjustment of Di2 seems fantastically easy and intuitive.

Shimano 7900 Di2, on the road

Since the install three weeks ago, I’ve been riding the bike a lot. On lunch rides, a weekend hillclimb race (that evolved into a 5-hour training ride), and even an 11-hour epic road ride (that included an hour-long rainstorm). I estimate at least 40 hours of ride time. I’ve yet to charge the battery.

My first impression is overwhelmingly positive. Obviously the “wow” factor is undeniable, but the bottom line is that it works very, very well. I have a few small nitpicks about shift button placement and size, but by and large, the shifting is so fast, so precise, and so easy, it’s hard not to feel addicted to this new game in gear shifting.

Shimano Di2 Install: Routing the Di2 wires can follow more or less the same path as shifter cables and housing would.

Shimano Di2 Install: Routing the Di2 wires can follow more or less the same path as shifter cables and housing would.

Photo: Zack Vestal

Shifting across the cogs happens as fast as the buttons can be pressed. While some may be bothered by the lack of a multi-cog sweep of the shift lever, in reality the shifting is just as fast — it just requires several taps of the buttons. It’s hard for me to imagine a chain-driven drive train that shifts as well. The sentiment is especially so for the front derailleur. A powerful servo motor activates the front mech, and it’s audible, but not obtrusive. But the shift itself is so rapid and sure, it can be made under full power without a second thought.

The first thing I notice on the bike is brake lever ergonomics. No longer constrained by having to house mechanical internals, the brake levers and hoods have the most comfortable shape I’ve ever encountered from Shimano. The hoods are broad, smooth, and slightly square, with plenty of room to hook fingers under the bottom. The lever blades are curvy and comfortable. Even though I have long fingers, I adjusted the reach inward toward the bar quite a bit, which makes for a very comfortable pull on the brakes.

The shift buttons are placed to mimic traditional STI, with the small, aft button handling shifts to small cogs, and a larger, dimpled button for shifting to large cogs. The actual gearshifts are amazingly fast and precise, requiring zero thought or soft-pedaling.

What I notice first is that each button has virtually zero throw. Accustomed to at least 15-20 degrees of lever sweep to actuate a mechanical shift, pressing a button that barely moves feels very different. But it’s very nice, and gives a precise, modern feel.

Shimano Di2 Install: The Di2 group weighs 60 grams more than mechanical 7900, but 60 grams lighter than last year's 7800.

Shimano Di2 Install: The Di2 group weighs 60 grams more than mechanical 7900, but 60 grams lighter than last year’s 7800.

Photo: Zack Vestal

The other thing I notice is that while placement of the buttons attempts to mimic traditional STI, the adaptation is not perfectly seamless. The smaller, aft shifter button is just like its mechanical counterpart, so that aspect is easy.

But from mechanical STI systems, I’m so accustomed to a big, broad shifter paddle (the entire brake lever blade) for shifting to large cogs or rings, that it has taken me much more time than I expected to adapt to the much smaller (by contrast) dimpled button. The only change I would make to the entire system is building the dimpled button across a longer section of the lever blade — in fact, if the whole lever blade pivoted inboard, in a 2-degree button movement, I would be in heaven.

Aside from this one issue, I’ve had zero problems. Going in, I thought battery management could be problematic. But battery life is easily indicated on the “junction A” LED by holding a shift button for 2 seconds, and so far, I’ve had no need to charge the battery. I’ll just wait until the light shows red, then charge the battery for an hour.

Shimano Di2 Install:  The lower wire harness bolts in place of a BB cable guide.

Shimano Di2 Install: The lower wire harness bolts in place of a BB cable guide.

Photo: Zack Vestal

I also wondered how well the shifting would work in real world conditions. I’ve ridden for hours, through rain and even off-road, with no problems. I’ve yet to wash my bike, but I doubt that soapy water will hurt anything. I’ve yet to crash (thankfully), so I can’t report on the crash-safe mode. And I’ve not spent enough time to really report on durability.

More time will tell a better tale, but for now, the answer is that it works so well, I will probably bend my budget and offer to purchase the system at the end of the test period. I’m not sure I can afford it at $4000 or so retail. But if I can afford it, I will buy it. It’s that good.

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