FIRST had adapters for the six inch wheels. You will likely need to manufacture your own out of polycabonate or aluminum. Bore out this plate to fit onto the hub of the wheel, make sure it is thick enough to provide chain clearance to the side of the wheel. You will also need to index slots to match the spoke thickness, so add thickness for as much contact as possible. Index 3 to 6 holes through the plate (you need two of these plates per wheel) and tap holes (8-32 or 10-32) indexed the same in your drive sprocket. Then use nylok nuts as jamb nuts to lock the wheel assembly together at the sprocket side. If you are planning to use the keyway/live axle configuration in between bearing blocks, make spacers to hold everything in place. if you use a dead axle config, bore out the sprocket to accept the wheel bearing on that side for a larger "wheelbase". Hope this helps.
