What type of paint to use for a bike frame What's the best type of paint to use for painting bike frames, it's steel if that makes a difference? 

I want to do a custom paint job and mix a few colours in a gradient effect. Should I use enamel paid, or an off the shelf car paint etc?

Also what paint should I use for an undercoat, a car primer paint ??

many thanks
Basically any paint that could be used on a car will work on a steel bike frame.

The better the paint the more robust it will be. Two-part epoxy based paints or powder coating are probably your best bets, but require specialized equipment. I think there are epoxy paints that do not require curing in an oven but you still need a spray gun. 

You can probably use aerosol can paint with a self etching primer, meticulous preparation and good technique.