I have a powdercoated bike that I want to put some decals on, but want to clearcoat over them. Will this work? Should I sand the powdercoat like paint before I put on a clearcoat?

No, don't sand it. I just had a frame powder coated, and the guy just sprayed clear on after. Just make sure you have high quality clear, and not some crap in a spray can.

I would add that we wiped down the powdercoat of my Super Sport frame with an automotive wax and grease remover which softens the powdercoat to give "tooth" to the clearcoat. Also, the first coat of clear should be light so as not to bubble or raise the edges of the decals, and that first light coat should be allowed to dry for 24 hours. Then lightly hand sand the clearcoat with 1000 wet-or-dry to provide tooth for a second, heavier coat of clear.

Scooper - NICE paint job !!!

Knock down the gloss of the powder coat with a scotch bright pad. A wet clear will stick much better.