Rattle can painting a steel bike frame.......

[REKIBorter]

The Bike FAQ section has a good thread on rattle can paint jobs.

 

[hamster]

If it's that bad then why not Hammerite?

 

[gerryattrick]

If it's already black then keep the base sanded down a bit as the base coat, filling in any deep scratches or dents with filler. I've done it and it works well. Even though the spray paint is not as hard as powder coat, scratches won't look so obvious over a black base. With careful use of masking tape and a blade you can even keep the decals, just give a final clear lacquer coat.

For a hack bike it will be fine.