I have a 77 Schwinn Varsity I got for $15. I want to Single speed it. It has the origional 27" rims on it. Is it easy to convert these old rims to singlespeed and what is involved. My local Performance said they didn't have the tool to remove the cassette from the hub. If another LBS can get the cassette off what do I replace it with? Perhaps a bmx style freewheel? The cassette says "Schwinn Approved France Made f3"