Shimano, makers of high-end bike gear I can't afford, is making a push for its Di2 battery-powered gear shifter. Why make the time-tested bicycle design more complicated and harder to service? Aerodynamics.
The Di2, which costs a prohibitive $4,000, uses very sensitive paddle shifters placed just behind the brakes. The front derailleur has a tiny computer that decides the gear based on the position of the rear derailleur. The problem is that it's powered by a little lithium ion battery, which of course has a limited range; a bike equipped with the Di2 can't run without the battery. The system is designed so that shifting the front gears is taken care of and the rider doesn't have to shift his body, causing wind drag. Allegedly it shaved nearly two seconds off Tour de France rider Chris Boardman's time.
But for us daily commuters, our loyal, analog, manually-shifted bikes aren't going to have batteries in them any time soon. I can shift on my own, thank you very much. [NYTimes]