I just wanted to point out that lots of stuff is a whole nother animal except Shimano 7/8/9sp from ~1990+. Old 5/6/7sp stuff is all different, newer 10sp stuff is different. As far as road stuff goes their dura-ace stuff has often not been compatible with the rest of their line. I believe Compagnolo stuff has all Sorts of intricacies between the different line-ups, though that's just from reading. I've never owned any of their stuff. SRAM did do a good job making their spacing the same as Shimano's modern 7/8/9sp spacing, but I think that's about it there too for compatibility? Anyway, it's not as simple as it should be. It just so happens that, for the most part, things work out for our current stock of MTB components, but that's often not the case. I'm not trying to "prove you wrong" or anything. I just don't want some newbie without much knowledge to do a search(like that's gonna happen? lol), come upon this thread, and assume that they can mix and match parts and end up wasting some money. Pretty soon with 10/11sp stuff becoming more standard, it's going to get even more difficult to match things up. I say we MTBers just move to the sealed BB transmissions and do away with derailer crap all together. Hopefully more of them will become available for more affordable prices in the near-ish future.