Originally Posted by Chefs20

Thanks guys for your quick replies. So, I will keep the 8 speed cog and put the 9 speed DR on with a 9 speed chain Your existing 8 speed chain should work fine unless you felt it needed replacement anyway. IF I keep the 3 gear crankset, will that work out? If your new 9s RD has the correct cage length to handle the chain wrap needed for a triple crank.What shifters should I buy? Unless there is something wrong with your current shifters there is no need to replace them. Just use the existing 8 speed shifter so it never wants to go to a ninth gear? There is no 9th gear if you're using a 8 speed cog and shifters. The RD doesn't know what speeds it's being used on or care. The shifter controls # of speeds. I run a 9 s RD on my daughters 6 speed bike.