Sounds like you're trying to do this the hard way. Our Electra cruisers came with Shimano 3 speed hubs. I thought the bikes were slow and heavy, until I checked the tire pressure. Seems the shop delivered them with about 25psi. I bumped that up to 60psi, and the bikes took on another life. Any steel frame, a 3 speed hub, some light hoops and a high pressure, fast-rolling tire would serve your purpose.