Did you make the hole too big? What hub are you using? You may be able to salvage it.
I mounted mine on a hi stop coaster. The stock cog fit right on, but the replacement 36t had a smaller hole (front freewheel cog). I used a half-round file to grind out the center incrementally, and used the pedal side chain and crankset to turn the cog on the file. I opened it up enough to fit in a short time.
If you have a common freewheel or cassette hub for geared bikes, check out the hybriped sprocket adapter, $50. I'm getting one for my next motorized bicycle if it isn't friction drive.
Originally Posted by MarkSumpter
Cursed a Rag Joint sprocket to high **** and back for not lining up well after almost 3 hours of grinding out the sprocket hole and mounting the darn thing...