You can put 8 of 9 cogs of a 9 speed cassette on and get new shifters and a 9 speed chain. True 8/9/10 speeds require a new freehub and redishing the wheel. It also it requires widening the droupous for the wider freehub. 7 speed freehubs are spaced 126mm and 8/9/10 are spaced 130.