I really think this is excellent, combining the colorful grafitti with a silhouette against the sky. Riminds me of the ET movie riding a bicycle silhouetted against the sky, But combined with the color, makes it even better. Our Lakewood skatepark has no grafitti at all.
I'd like to see the camera angle just a little more to the right and lower. To get body from waist up against the sky, and just a slight touch of spotlight on his skateboard-only by an assistent. A Lower angle would make him higher in the air, too. Yes flash, but only to emphasize the skateboard.
I like the composition. Wish there was a bit more light (personal preference). I have a few skateboard parks near my house. I will try to emulate what you have done here.