Originally Posted by Raiyn
A 9 speed cassette WILL fit a 9 speed hub. It will NOT fit a seven speed hub
I think what was meant here is that 9spd cassettes fit on an 8 or 9spd hub, but 7spd you are up a creek since its narrower.
Like I said though, on a 9spd cassette you are only getting harder gears really.