I try to paint my old steel exerciser Fuji a different color every year. The rattle can paint is not very durable and takes FOREVER (weeks) to dry thoroughly as a previous poster mentioned, but I do a passable job. I strip the bike to bare metal every time though and I've found that the easiest way to do it is to use paint stripper paste (available at Home Depot) and many small brushes and rags. Much much quicker that sanding.
BTW, Home depot sells a spray can paint that they call "appliance" paint. It's supposed to dry harder-- like the paint on your washing machine. I had fairly good results using it last year although colors are limited (black and white I think).