When it comes to drivetrain parts, i.e. derailleurs, cassettes, cranksets and chains...... apart from wieght, is there a scientific reason why dura-ace should be any better than, say, Deore? I chose a road v mtb on purpose.
I think the only feature that would make a difference would be engineering tolerances, i.e. less "play" in the better gear. However, I doubt there is a measurable difference between the various groupos.
Maybe the lighter weight of the derailleurs may mean it can accelerate more quickly to its new position during a change. I find this hard to believe though because of the tiny distance that the derailleur actually moves.
The shapes of cogs and gears and chains is the same across the range, it's only the materials that seem to differ.
Finally, the lower tech materials may actually be stronger and outlast the higher tech materials used on the expensive groupos. The material choice seems to be for weight saving rather than endurance.
Is groupo choice more an issue of road "cred" and fashion rather than science?
Of course I'm sure we all agree that the very minor weight difference is irrelevant when we look at the total weight of rider plus bike....