I am pretty new to cycling, and bike mechanics, but i have been building and racing cars and motorcycles for years, so i have a pretty good technical understanding of most basic mechanisms.
can someone explain what the difference is between a "good" rear derailleur and a cheap one?
i have read a lot of reviews and i understand that the better RD's shift more smoothly, more precise, etc etc.
it appears to me that they are all made relatively the same. So, weight aside (i could care less about a few grams here and there for what i'm building) what is the difference between a Sora and a Dura Ace RD (Mechanically speaking; spare me all the "it feels better, shifts smoother fluff please)?
I'll be building up a cyclocross bike soon, and i want to know where to put my money.