The video shows off Shimano’s new for 2009 electric Di2 Dura-Ace and their new 7900 “regular” Dura-Ace. Ã‚Â In particular, we got them to demo the auto-trim function of the front derailleur. Ã‚Â It “talks” with the rear derailleur and keeps itself positioned properly to avoid chain rub regardless of where you are on the rear cassette. Ã‚Â Pretty sweet. Ã‚Â Following that is info about the new 7900 group, and we’ve got some detailed pics for ya if you read “more”…
This angle shows you the dramatic outward angle of the brake levers, making them easier to shift by reducing the inward angle you have to achieve to make it shift.
The 7900 shifters now have reach adjust. Ã‚Â Simply remove the little front panel and adjust a forward facing screw to move the little barrel (orange arrow) forward or backward to change the reach. Another feature is the direct cable routing which helps increase the pull strength for the brakes.
The new crankset uses a hollow big ring, and the small ring bolts directly into it. Ã‚Â This makes it easier to change the rings since no special tools are necessary. Ã‚Â Goodness knows typical chainring bolts like to freeze up or just spin or come loose on their own…aaargh! Ã‚Â The only downside (besides another proprietary Shimano bolt type/pattern) is I’m sure this ring will cost a fortune to replace…
Another innovation for 2009’s 7900 Dura-Ace is a directional chain. Ã‚Â Not sure whether you have to run this chain, but given that both the inner and outer links are perforated as well as hollow pins, it should be pretty light. Ã‚Â The ramps and grooves are designed to speed shifting based on the direction of the shift and reduce chainsuck. Ã‚Â Above is the inside of the chain, below is the outside.
The rear derailleur now has carbon pulley plates and can accept up to a 33T cassette (according to their website). Ã‚Â That should mean it’ll work with some MTB cassettes on ‘cross bikes. Ã‚Â It’s made to work with a wider range of gears, including the new 7900 11-28T cassette.
One thing they didn’t have on hand to show off is something I’m pretty excited about: Ã‚Â Their new Flight Deck, coming in the Spring, will have incline and altitude and HR functions, all wireless. It will also have wireless PC connectivity…hmm, Macs? Ã‚Â I’ve run Flight Deck for years, and it was largely the deciding factor when I built up my new road bike as to why I went with Shimano. Ã‚Â The ease of use and ability to get Cadence without running additional sensors or wires, as well as showing what gear you’re in on the computer, is freakin’ sweet. Ã‚Â The only complaint is they moved from a two button design on one controller to a single button on each side…and no matter how much I try, I keep hitting the left button and stopping the distance/timer mid-ride whenever I change hand positions.