shimano fc4400 double chainring replacement
BCD is the key, Shimano 9 and 10 speed chainrings are interchangable. Dropping a couple of teeth is not a problem, just adjust the front derailleur and check the chain length. Really focus on the BCD, as Shimano road has standard and compact chainsets and they can both take 50 tooth chainrings. You probably have a 130 BCD, if you are running the usual 52/39, the 110 BCD compact chainsets are usually 50/34.