I Was starting to read somewhere that epoxy paint + polyurethane overcoat is a good combination and is quite strong.If i want to sell it for even medium amount money it must look good,so its a good question will this kind of coating be resistant on a bike frame.I could cheaply make it since i have both epoxy and poly paint at disposal and i have a paint spray machine .I used it to paint poly and work on old cabinets of antique clocks.I made mirror finish that way .If it will be durable i would not hesitate to use it .I may even like the bike that way since i can make all the details to the frame that i want.I can even paint it with different colours and choose the tone .The problem is that i never thought that poly can be used for that purpose yet in the archives on this forum i read something about it ,thought i do know that poly is a very resistant coating.But to what extent ?