You can do it with cans, you just got to do it right which takes time & patience, & lots of cans of paint....
Beginning after bike is completely disassembled, frame is stripped to metal & cleaned...
General rule number one, "a can is a coat"...
When you spray, you are going to follow the "multiple thin coats 2 or 3 minutes apart" like it says on the cans, until the can is gone & then call that a "whole coat"... what you are doing in the "2 or 3 minutes" is letting it flash over after each pass over so that it doesn't sag, so you can even wait ten minutes or so between each thin "subcoat", if you will, plus because spray cans spray wide you waste a lot of paint, that is the first main con to spray canning a frame, so, yeah, 1 can, 1 coat(of briefly spaced thin coats)…
2nd general rule, "let it sit"....
Forever...
At least 48 between each can, or "coat of subcoats"...
I recommend just blowing it off & finding other things to do for a week between each coat...
Then hit it with some wet 600 or 800 until it is nice & smooth...
With the primer, you will probably sand through the first can/coat in some places but that is ok because you are going to repeat the whole process a couple more times sanding off less & less each time, by the third can of primer you should only be sanding of the roughness from the "spray can effect", as I call it...
So do exactly that process with each coating step...
& you WILL have to deal with the "spray can effect" between each coat, that is the second major con with canning...
The "spray can effect" is that roughness you get from the way spray cans spray, on a flat sub straight you can spray one direction & avoid it but on a bike frame it is unavoidable...
Which means you WILL have to do a color sand & buff & polish back to mirror like one would do with a car body as a finishing process...
The coating steps are...
primer, a self etching metal primer, or something comparable or better for metal, at least 3 cans/coats
Color, or base color if multicolor, I recommend doing only one color if you are going to do spray cans, 3 can/coats
(If doing multi color then sit time should be much longer between each final can of each color to avoid tape marks...do your three coats, with a couple days in between & wet sand & after the third coat/can let sit for a week, than wet sand, than let sit for another week, than mask & do next color)
Then each other color accordingly & as much as necessary in coats equal to a whole can in relation to area, so like if it is just a stripe or what ever, spray it with a few briefly spaced coats, then sit, sand etc...
Then clear coat, depending on what kind, like six coats/cans...at least...
following the whole "subcoats", sit, sand process between each one meticulously..
Color sand/buff/polish grit order..
600, or 800, I usually start with 800
1000
1500
2000
3000
liquid buff rough cut like a Maguire's "8"
Then a "5" or "4"
Then a fine cut like "2"
& if you want to get really fancy finish of with a super fine swirl remover...
Its a lot of work & takes a while but that is how you do it with spray cans...
many coats, lots of time between each coat, lots of sanding & color sand/buff/polish....
Oh, & always meticulously follow can instructions, temp, humidity, etc, etc, get on google & search "local weather" & schedule your spray times by the weather to be sure the humidity is low, temp moderate & wind minimal if spraying outside..
& SHAKE THAT CAN, shake it till you cant hardly shake it any more than shake it a little more...
& clean, clean, clean...between every step...
& rubber gloves, tack cloths, the whole nine yards...
No skin oils or dust....