You can read our original post on this here, but figured there’s enough information floating around out there to warrant a followup.  First, the “official” group shot from Shimano:
Now, we’ve found the weights of the components and a few rider reviews, quotes and miscellaneous info, after the break (read more).
The complete Di2 group will still be approximately 113g lighter than the current 7800 groupset – but around 68g heavier than the standard 7900 mechanical group, according to Shimano. A wired set up was chosen over wireless, which would have required multiple batteries and added weight (speaking of the battery, it should be good for over 600 miles per charge and fully recharge in about 1.5 hours).
- STI Dual Control levers (ST-7970) – 255g/pair
- Front Derailleur ( FD-7970) – 124g
- Rear Derailleur (RD-7970) – 225g
- Battery (SM-BT79) – 68g
What’s the benefit?  Besides slight weight reduction (from 7800), shifting is quicker, more precise and requires less effort.  The components also self-adjust constantly and after a crash, so it should be pretty much “set it and forget it”.
The Di2 setup will be sold as an upgrade from the standard 7900 group, which is preselling for around $2,600 and available January 2009.  The Di2 parts can be used with remaining 7900 or 7800 parts that are non-electric. US pricing is TBD, but UK pricing, shown below, should allay any concerns that it will be cheap:
- STI Dual Control levers – £349.99/pair
- Rear derailleur – £349.99
- Front derailleur – £249.99
- Cable set – £99.99
- Battery – £49.99
- Charger – £49.99
- Chainset (Dura Ace FC7900) – £319.99
- Cassette – £129.99
Wired magazine has a nice interview with several pro riders and secret development types at Specialized about this system, or check out Shimano’s Dura Ace site.  Bicycling Magazine will have a ride review in their October print issue.
