Is there a do-it-yourself way to tow a kid's bike? We drop our kid at school in the mornings, and I'd like to bike over to pick her up after school.  I've picked her up on our tandem (that's one reason I got the tandem), but she'd like to ride her own bike some of the time.

So I need a way to take her bike with me, something like this, I guess:



...except I don't need to be able to support the weight of the kid on the bike, I only need to be able to tow a riderless bike.  So I'm trying to find a way to do the same thing that's cheaper (hopefully) and lighter (and maybe smaller?).

One possibility (that I'll try) is to simply strap her bike to the back of the tandem.  I'm sure that will work, but I'd also like a system that works if my wife is the also riding the tandem and a system that would on a single bike.
If the child's bike has a quick release front wheel, you could also use a universal fork mount bolted to a rear bike rack. Then just hang the front wheel on the kids bike with a bungee cord.