Repainting an old frame

[Mububban]

My almost 4yo son has inherited a hand me down bike, still in good rideable condition but seeing as it came from his big sister, it's pink He'd like it to be fluoro green instead.

Will a can of enamel spray paint from the hardware store do the trick? Will it bond properly to the existing frame's faded and chipped old paintwork on its own, or will it require any sort of prep/primer? This bike only needs to last him a year before he outgrows it, I don't want it to end up looking all scabby and gross but on the flipside I don't want to overthink it if it's going to be a huge endeavour

[ldrcycles]

The easiest way to do it is get it sandblasted and then a primer powdercoat, my local sandblasters do that for just $33, and then you just spraypaint whatever colour you want.
Normally getting a sandblast and colour powdercoat is about $70, maybe you could find cheaper but in any instance there's no question that is the toughest finish you can get so it would be ideal for a kids bike.

If you want to spend the absolute bare minimum though, you will need to sand the existing paint back to a point where you at least have a consistent surface, ideally it's best to go all the way to the bare metal (which is where sandblasting comes into it, because hand sanding takes FOREVER). You may be able to just spray your preferred colour straight on but i've never had any luck with that and you can get a can of primer for $4 from Super Cheap Auto. On that note, i've found the spray paint from SCA to be much better, as well as cheaper, than the cans from Bunnings.

The other points with rattle can painting are to pick a day when it's hot and dry (which helps the paint cure), sit the can in the sun for a few minutes to heat up before starting (which helps the paint to flow better) and get your technique down pat, just slow enough for the paint to look wet but fast enough that it doesn't get runs in it.

[bychosis]

If it's only for a year just grab a can of your favourite colour of car touch up paint, lightly sand the existing frame back and put on by few coats. Not much effort, not much $ and unless it has a lot of rust under the paint or is left out in the rain a lot it's going to last 12 months.

If it starts to look too daggy before upgrade, rinse and repeat.

When my 9yo was learning to ride i did similar, but ended up with a couple of coats of clear as well and the bike still looks OK and is ready for rider 3. Few chips and scrapes, but nothing really nasty. The bike is kept inside (mostly) but certainly didn't get any special treatment.

[V8rider]

You can use a paint stripper to get back to bare metal rather than hand sand/sandblast. Then use an etch primer, then colour, then clear coat for the bling look. I've done this myself for the exact same reasons. Plenty of youtube vids of the process if you're really interested.