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Shimano Dura-Ace Di2 electronic: first ride

The 'JCT-A' will carry signals from the two Dual Control levers and channel them to the main wiring harness.

  • Shimano's new Dura-Ace Di2 electronic group may or may not be a marketplace success but it could possibly change our perspectives regardless.
  • The Di2 Dual Control lever is virtually empty inside. As a result, the lever body is markedly more compact than its 7900 cousin and is more in keeping with Shimano's ideal.
  • In practice, the Di2 lever actually feels rather similar to the outgoing 7800 unit but thankfully, the electronic version's body still seems to yield a flatter perch up top.
  • The Di2 lever doesn't just look smaller than 7900; the body is substantially smaller in girth and it's also 100g lighter.
  • The shift buttons felt somewhat small in use and the differential texture is well-intended but it's still hard to tell the two buttons apart in the saddle.
  • Di2's carbon lever blades are wider and flatter than 7900, plus they're not canted out as far.
  • Shimano fitted Di2 with a reach-adjustable lever like on 7900…
  • …although the Di2 version looks far cleaner when the reach is shortened; there's no unsightly gap as on 7900.
  • The button throws are fantastically short but they still require a relatively firm push thanks to the collection of springs that lie behind them.
  • This will be a more common sight if Shimano gets its way.
  • The compact battery is supposedly good for 500 charge cycles and is
  • Shimano has managed to integrate the battery mount fairly neatly with this aluminum bracket. We're guessing it can also be 'massaged' to fit, depending on specific frame shapes, but it'll invariably still be pretty unsightly on some models.
  • A lever pulls the battery in tight and the o-ring seals should hopefully hold up well over time.
  • Shimano claims a dead battery can be fully recharged in just an hour and a half.
  • Shimano said this tangle of wires was a small price to pay for the lighter weight and better reliability as compared to a wireless setup.
  • All things considered, this doesn't look as bad as it could have.
  • This setup strikes us as a bit jury-rigged but we'd imagine that future setups will get cleaner as frame manufacturers develop dedicated routing solutions.
  • The main wire runs the full length of the down tube and is well-masked on this black frame…
  • …but these little adhesive wire guides will surely stick out like a sore thumb on any other color.
  • This little widget replaces the standard bottom bracket cable guide and serves as a junction point for the incoming and outgoing wires.
  • The 'JCT-A' will carry signals from the two Dual Control levers and channel them to the main wiring harness.
  • The small LEDs display battery life and are used during the initial setup.
  • Shimano abandoned the auto-adjust feature of earlier prototypes for the production version to save some weight.
  • In fact, the two rear derailleurs look strikingly similar from the upper knuckle forward.
  • The standard Dura-Ace rear derailleur houses the conventional coil spring within the parallelogram but the Di2 unit just needs the stepper motor.
  • All of the wire connections are tightly sealed with o-rings and our exceptionally wet test ride at the Suzuka race track at least suggested that they'll hold up ok.
  • As with the mechanical version, the 7970 rear derailleur will use a carbon pulley cage. The mechanical spring only serves to minimize the slop inherent to a geared stepper motor design.
  • The front derailleur is arguably the most radical looking bit with its bulbous top.
  • The bulky plastic housing contains both the stepper motor and system CPU so it's understandably sizeable as compared to the standard version.
  • The additional hardware on the electronic version also necessitated moving the limit screws to alternate locations.
  • Like with the rear derailleur there are still mechanical springs to aid in positioning precision.
  • Handy tags identify what wire is supposed to go where.
  • The wire connections are actually so tightly sealed that Shimano will include a special tool to pry things apart when needed.
  • And yes, Di2 does seem to work in the wet.
  • The old Shimano AX group was billed as a more aerodynamic package but no one cared much about cheating the wind when it was introduced. It's arguable whether or not the public is ready this time around but we have a feeling Di2 will fare much better.
  • Shimano made a lot of effort back then to tuck in the AX's shape as close to the frame as possible.
  • Ironically, the center-pull AX brake is now a design that is mimicked for its aero profile.
  • Shimano's AX group was perhaps ahead of its time; will consumers say the same thing about Di2?

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The 'JCT-A' will carry signals from the two Dual Control levers and channel them to the main wiring harness.

© James Huang