Originally Posted by
rogerstg
I'd say the opposite is true. Heavier is usually heavier duty and lighter is generally more fragile.
Not necessarily in the case of a drivetrain. Better quality materials and features "can" possibly weigh less. A good example is how the Dura Ace Rear Derailleur can supposedly survive a crash because of it's build quality while being lighter.
BSM has put together what I believe to be one of the most detailed explanations of what goes into Ultegra & Dura Ace:
http://www.bikesportmichigan.com/fea...-ultegra.shtml
A 105 VS Ultegra exchange...
http://www.beginnertriathlete.com/di...187662&posts=7
Ultegra is much closer to Dura Ace than it is to 105.