To elaborate a bit more, I was wondering if there's some online site where reviews can clearly tell you for example if this or that model of a drive train is better according to USER reviews.
I know Amazon has decent reviews, but I was thinking more of a site specialized (no pun intended) on bicycles only.
Sort of like newegg.com for computers and gamers, but for bikes.
The reason I ask this is because I keep looking at Shimano spares for example, and their site seems (to me at least) not very clear on providing much specifics on what it is that makes this specific part better or that more expensive, etc.