I want to take my two older children to school by bike. Ds1 is nearly 6 and dd is 3.5. Ds1 has been using the trailer bike for a while and is great with it but he's not ready to cycle on the roads by himself. I've recently seen a couple of people using delivery bikes/trikes with a big box on the front to transport up to three children around. Do you think this is safe? It seems as safe as a trailer to me, unless I'm missing something, esp if one can rig up some kind of seat belts inside. Or what about a normal trailer? I think ds1 might be too big for one of these now, but perhaps I'm wrong. Would really appreciate any thoughts from the cycling crowd.