I made this a while back. To allow my daughter to go on longer bike rides I got a bike trailer. Of course she would like to ride on the easy parts, so I added a bike rack to the bike trailer to carry her teeny bike. Its made with 1x1 ash, a couple of u-bolts, and a few nuts and bolts.
The bike on the rack is an 8" frame bike with rear suspension. Pretty amusing on a little kid's bike. It was a prototype bike we got at Bay Cycle in Whitby. The bike rack carries a 10" bike nicely too.