After the much hyped Dura Ace 9000 has been floating around for a while, details were released today about the new Di2 group which will be numbered 9070. Expect significant changes in the styling and functionality of the group; the most significant highlights are discussed here.
You've already seen the crankset several times in the past. But now we get more information on it: Shimano is offering the crank in a single BCD. That's right, gone is the standard and compact options, replaced by a single 110mm, 4 bolt BCD. The hollow chainrings will be available in a multitude of sizes from compact to cyclocross, standard and TT configurations. Supposedly, the chainring design allows any chainring produced to be stiff enough to work with the compact BCD. Be wary though, those chainrings won't be cheap, so choose your gearing very wisely or be prepared to lay out a large sum in order to change it out.
Now onto the meat and potatoes of the new group. Along with the individual components shown, the new Di2 group is going to be getting the thinner E-Tube wiring configuration first seen on Di2 Ultegra. It will also feature a revised junction box with a charging port on it, negating the need to remove the battery to charge it. This feature is especially useful for hidden batteries, which Shimano claims they will be supplying to bike companies and selling aftermarket as an additional part for their PRO seatposts.
Along with the charging port, it seems that you will be able to plug in several different configurations of bar shifters along side the STI units. This means you may be able to run clip-on aero bars with TT shifters for a morning time trial , and simply unplug them for the afternoon road stage. The versatility this represents is huge.
The star of the show, the shifters, appear to be completely redesigned. The hoods feature a dual density rubber to cushion the hands more efficiently, the body is thinner overall, the brake lever shape is subtly different, and the mechanism of changing a brake cable is simplified. Most importantly, the shift buttons are made larger and more tactile, for use with full finger and winter gloves. Early reports indicate that the shifter will be programmable in order to allow for multiple shifts when holding the button down (similar to Record and Super Record EPS.)
The rear derailleur gets an aesthetic redesign and drops some weight, along with being slightly more compact as an overall unit. It receives the same two-tone black and polished finish as its mechanical brethren (although in photos it appears to be white as opposed to polished.)
The front derailleur again receives the black and polished (what appears white in photos) finish as the mechanical version. The overall size of the electronics are reduced and the wiring configuration has changed from plugging into the front of the unit to plugging into the rear (presumably to better hide wiring.)
Perhaps the most exciting thing to come out of the announcement for me is the inclusion of the new Flight Deck computer. Supposedly, it will be ANT+ compatible touchscreen (like the Garmin 800) with options for gearing indicators, charge indicators and all the regular computer functions. No word on it being GPS compatible yet, as many rumors had stated. Also no word on if there will be programming features built into it for use with the new 9070 group. If this were to be the case, it seems logical that we'll see software hacking and new features added by outside sources, along with the ability to download firmware updates directly to the system through the Flight Deck.
All in all, an interesting set of features. Still, for around $4000, I don't think it will be high on many people's wish lists.