I am going to convert my 6 speed to be a 9 speed. I know I will need to replace the freewheel to a 9 speed cassette (I have a new wheel), shifters and chain. I am also replacing the rear derailleur. I thought I once read that the crankset will need to be replaced also, because of the spacing between the chain rings will allow the 9 speed chain to fall between the rings. I have seen a lot of info about upgrading, but I haven't seen the need to replace the crankset. I don't know if I thought I read that once or not. Does anyone know if I will need to replace it? The crankset now is a Sakae CR.