Thanks for the feedback guys.
The Tig, you mention "images each with a unique style" that would be interesting too. But the plan is that they will all be from the same artists and will be in the same style as the tricycle.
The only part that I am thinking over is the color schemes at this point. The current plan is that the bikes will always be blue but have different accent colors (Green, Purple, Red, Yellow), but I did have the thought to make both the bikes and accent colors change, I just thought that seemed too busy for me.