Hi Ian,
Thanks for your entry. I like the fact that you took a shot at one of our favorite concepts. The result has strong graphic appeal, to be sure (great work on the colors and comic style visual!), but I think misses some of the danger and fun in the idea. What might work better is a very wide, low-angle perspective that shows the tricycle taking flight, and then a giant smile with a look of part terror and jubilation in the kid's eyes.
Here's an example of something sort of similar (although the perspective is wrong, and the smile is missing)
http://www.google.com/imgres?imgurl=http://www.istockphoto.com/file_thumbview_approve/5546740/2/istockphoto_5546740-tricycle-jump.jpg&imgrefurl=http://www.istockphoto.com/file_closeup/illustrations-vectors/vector-cartoons/5546740-tricycle-jump.php%3Fid%3D5546740&usg=__6LeoDbyHvraImrqCuSNMCvVta3Q=&h=333&w=380&sz=54&hl=en&start=14&um=1&itbs=1&tbnid=Y-wcwIhmIXnXIM:&tbnh=108&tbnw=123&prev=/images%3Fq%3Dtricycle%2Bjump%26um%3D1%26hl%3Den%26client%3Dfirefox-a%26hs%3DMiR%26sa%3DN%26rls%3Dorg.mozilla:en-US:official%26tbs%3Disch:1Thanks again for your work!