Way too big. The fact that this is your second work solidifies this statement even more... Pixel art is about having control over every pixel..., and I highly doubt you're going to sit and mess around with every single 200,000 or so pixels of that bike until it looks just right. In pixel art, one pixel can effect the whole piece, this just seems like a large painting done in MSPaint.
In simpler terms, start off a lot smaller--a 200x200 pixel canvas at most.