Now that I have some children I was wondering what the consensus was on a good age to let children on the back. My best guess is if they can reach all the way around me and hold their hands together, and are at an age where they can understand and follow instructions. And of course I did buy them a helmet that fits properly. My biggest complaint when trying to buy a helmet was that there are not alot of full face street helmets for kids. Everyone wants to sell you an open face, wouldn't you think that most people would want the same, if not better, protection for their kids?