I stroll into my local bike shop, aiming to get a road cassette, because often when I'm even riding around, I'm in the 16t-18t cogs in the back, and I rarely use the largest cog. So I go to the cassettes area, look at the SRAM 9-spd road cassettes, and I find one and ask a clerk if he's tried it and if it's a good 'un, and he just says, "Wait, you have a mountain bike right?" I'm just like, "Uhh, yeah, you know, my DB Assault." and he goes, "Well, with the MTB derailleur, it's just gonna be... funky..." I look at him, and he says, "Well, just because they aren't meant to be used together. That's why Shimano and SRAM make road cassettes, and they make MTB cassettes." SO, I just walked out of there, angry, because I got the feeling that if I bought it, they wouldn't put it on for me because of my crazy oblivious stupidity towards running a road cassette with a MTB derailleur. Is it really that bad to run a road cassette with an MTB derailleur (SRAM X.7)?