The 52cc Mite Be Better With The 1 1/2" Rubber Roller From Bmp. Not For Speed, But For Fuel Milage. Used My Gps Street Pilot On My Shifter Bike For Speedo. Got Up To 32 Mph In 5th Gear, Scary Fast With The Stock Spokes And My Fat Butt Over 300 Lbs. Never Got My 25cc Jackshaft Friction Drive Running. "zipcycle" Was Turning The Engine Backwards With The Electric Drill. Duh!! Ron