i think it depends most on their attitude and their feelings toward this sport. if they're really into it, they're going to have blast, if not.. well.. you could hope they have fun or not. the miles the kid can do in a day is only used to determine how far you can go each day, not how much fun or success you'll have (unless you measure distance traveled as success). but of course, as a parent you probably know this already... problems and issues? if your kid is into it, then the only problem i can think of is him being so sore he wont wanna do it again the next day. if hes not into it and you're dragging him along, then you're gonna have a crap load of problems