I started each of my children on extended touring when they reached 6 years old and could ride trail a bikes. (We did extended day rides on a TAB when each had reached 4 years old.) I was not comfortable touring with them at any younger age. For me, I wanted to start touring with them at a younger age, but considered the down side too great (diapers, cranky kids, bad child experience, injury, etc). I know that others have done this at a younger age, but for us that was the best answer. My oldest is now 13 and loves touring and has thousands of miles in. My youngest is about to turn 9 and also loves touring. I am glad we started them touring at 6. I have a friend that tried to start his son at 15 and he will have nothing to do with it. Last summer was the last year for my oldest on the tandem with me and my youngest behind the tandem on a TAB. This summer the oldest will be on his own bike with his own equipment and the youngest ditches the TAB and jumps up to the tandem with me. Good luck with your decision. My concern was that younger kids in a trailer day after day would be okay for the parents but boredom and a bad experience for the kids. I wanted them to be powering the trip, not just a passenger and my kids seemed to think the same.