Hm looking at the sig I'd say it looks great but then into the details. The lettering looks SLIGHTLY out of place due to the gradient not matching where the letters actually are positioned in the image. I can't really see much flow in it, the emphasis is clearly supposed to be on the rider but I keep having my eyes drawn to the background, ouch. Maybe blur the background a little, center the render and sharpen the the rider and bike?
On the edges of the bike where the lettering is behind I see white, if that's a glow I wouldn't recommend it, it's not really working. If it's part of the render go over the edge with the pen tool and remove it.