I have done 1 but not 2. If you disassemble the cassette you have your choice of gears down to 11 or 12 (try finding a 11 or 12 tooth BMX freewheel). You should be able to use the derailer but it would be ugly. I've seen knock off singulators here in Sacramento for $25. I bet with all those gears to play with you could find a combo that won't need a tensioner. There is a web site that has a calculator for just that, but I cannot remember it right now. Anyone else out tere know?