Another issue I failed to address is compatibility. Suntour shifters never played nice with Shimano freewheels. A replacement freewheel will be Shimano compatible but may not be compatible with the Suntour Express shifters. And the Suntour rear derailer may not play nice with Shimano shifters. Oh, and you'll definitely need a new chain. Sorry to say, Goose102, but you may need to replace more parts. It's not like they will be all that expensive but this is a pretty old bike and how much you want to sink into it is a call you'll have to make.