[jrockway]

A dynamo doesn't actually add that much load to the bike, but they're heavy and invasive, the exact opposite of what an electronic shifting system aims to be.

I run a dynamo generator for lights on my bike. The datasheet says it steals about 7 watts of power. I'm a relatively weak cyclist, but I can put out 230W continuously for an hour. The dynamo doesn't matter unless you're racing.

That said I still have good-old-classic 10 speed mechanical shifting. It works so well I don't see the need to add another computer-based gadget to my life.