If its any kind of steel (excluding stainless) you'll want to at very least clear coat it or you'll have a nice brown very quickly. The clear should stick ok to the metal as long as you don't polish it smooth. And make sure you coat it very thoroughly as not to miss any spots (at least two coats) then let it cure completely. Then if you are planning on putting stickers on is lightly sand the clear with very fine sandpaper (is wetsand 1000 grit) then get it good and clean and let it dry. Then apply the stickers and give it another two good coats of clear. And make sure to use plenty on the chain stay and or a chain stay protector. And don't be in too big of rush as it will take time for the clear to cure and not be soft. Do not re assemble the bike until its fully cured or all the work you do will have been for nothing. I suggest letting it cure for a good 3 weeks minimum to be safe.

Hope this helps. But to be honest I'd check to see what a local body shop would charge you to spray it with car clear coat because it will be much more durable and cure a lot faster.

Good luck.