Basic drivetrain queries for the roadies...

it's funny because, as ludicrously expensive as that derailleur is, its totally worth it for the right context. if you're a top racer and cost is of no consequence, then it's quite a big weight saving. However, for grunts like us, 30% lighter for many times the cost is ridiculous. just an observation but fascinating i think. technology that is.

i can't believe i'm getting excited about derailleurs again :-I

how much? you could buy a bike for that!

but most racers will not be using them. why? because weight isn't everything especially not somewhere like the derailleur. pro-tour bikes have a 6.8kilo/15lb weight limit which is quite easy to achieve, bikes for the spring classics often weigh more than that. rotating weight is where the weight saving is and where the money is spent.
and ultimately reliability and precise shifting is more important.