so i have been looking at all different types of cassetts for my downhill bike, and i came apon this..Sram PG 970 Road Cassette 9 Speed 2007 which if i buy would go on a mavic deemax rim and hub, do you guys think this cassette would work good...for some reason i herd that the road cassettes would be a little better than the mountain ones?..or any other ideas..