8 of 9 will not fit correctly on your bike and wheel's feehub. Both an 8 speed and 9 speed and 10 for that matter are designed for 130mm dropout spacing. 8 cogs out of 9 comes out to about 126 which is what some people with older 7 speed wheels do as 6/7 speed cassettes are designed for 126mm droupout spacing with matching hubs.