It looks like I'm going to have to modify my Panasonic to SS for now. This is mainly because I need a simple college commuter that I can ride, take on the train and lock up at school without having much to think about. I have a spare rear Sanshin wheel that I would like to remove the 6spd freewheel and put on a BMX freewheel or whatever fits. Can this be done? And if so, would someone enlighten me on the threading... is it "standard" or "metric"? TIA