Gear transmission

this is how i´ve made the bikes main gear transmission, it´s a 3 sprocket standard main gear had to buy 2 sets i´had to drill out the rivets that holds it in place and place a 9mm spacer between the 48 tooth gears otherwise the chains will rube each other.I´m using the small gear e 2 large ones.than i´had to enlarge the center hole of the small gear to fit a stardard 16 tooth freewheel and hold it by 3 screws.The 3 main gears is hold by 5 6mm allen screws. Next was to machine a freewheel threaded holder, you can use a rear wheel hub to make it, it´s about 16mm long with a blind hole thru it, the thing here is to keep the chain line the same as the stardard chain line.Next was to make a spline shaft to hold a bmx 14 tooth freewheel to the motor, again i´ve machined one but you can get a spline shaft at your local bike store and bolt it to the motor housing.I had to replace the bike´s down tube by a 2mm wall 40mm square tube , bike´s frame was flexing too much with the original down tube.