I made a chopper last summer. Use a bmx frame and bolt on mountain bike forks and use the 18 or 20" bmx tires. I drilled "bullet holes" all down the frame and put .22 shells in them. I could go into alot more detail, but I don't feel like typing a whole lot. It was a sweet bike though. My next bike project is going to be putting a chainsaw motor into a mountain bike and have a 21-speed transmission!!
Justin ~hondaATCman~
'82 Honda ATC 110
'81 Honda ATC 250r (Summer Project)
'87 Suzuki LT 250r Quadracer - Very Modded...FAST!!
'03 Yamaha Big Bear 400 4x4
'85 Ford Bronco II 4x4 2.8 V6