I talked with Ben at the Shimano booth. Yes, I had many questions about the batteries for the new Dura Ace electronic shifting offering. Ben was extremely gracious and put up with me constantly interrupting him and asking yet another question. First, the retail cost of the system is set at about $4000.00. He asked what I thought of it. And I am not really sure. I like that I can fix my bike without electricity in the middle of no where. And I don't like to charge or carry batteries or battery chargers. However, I do think electronic shifting might be the future. For those those making a living on a bike, and racer feedback is what drives the performance aspects of the bike industry, electronic shifting might be a dream. I tried it on the demo bike. You exert really light finger pressure on the textured or the smooth part of the lever paddle to up and down shifts. You don't push the levers at all. Not even as much pressure as pressing an elevator button.
Here is the battery skinny: They are lithium ion batteries take 1.5 hours to charge from 0 percent to 100 percent. They weigh 68 grams and give you about 2000 km of electronic shifting, about as much mileage as a riding a Tour de France on one charge. This means you can buy two batteries, and put one in your saddle bag. They weigh about as much as an energy bar. The hotter and flatter riding conditions make them last longer than hilly and cold riding conditions.
You can check the battery charge at any point in time with a light unit that sits on the cable under the handle bar. Green light steady is 100 percent. Flashing green light means 75 percent charged. Red light is 50 percent charge. Flashing red light is 25 percent charged, and it will flash by itself. If you choose to ignore the red flashing, you will run the battery down. The almost last 10 percent of the 20 percent energy left state goes to the front derailleur, and then that will stay in whatever ring you choose. The very last 10 percent goes to the rear derailleur. When the battery dies you are riding that single speed you always wanted to build. So, you thrill seekers in the Alps who are bad at details and frequently forget to charge your cell phones, Blackberries, and cameras, choose your last shifts wisely.
The battery compartment has O ring seals, and Shimano has been testing the set up with professional Tour de France peleton riders as well as pro cyclocross riders. No moisture or mud short circuit worries. You get 500-600 charges to 1 battery pack. The Dura Ace 7900 group set components can all be use for the Di2 Dura Ace electronic shifting, with the exception of the derailleurs front and rear, shifters, and battery.
Photos by Wheelgirl at Interbike 2008 in Vegas
