I highly advocate starting youngsers off with a recurve or longbow. It' s amazing to me how well and fast they pick up skills required to shoot them. A lot faster then adults. I have my son who is now eight shooting a 15 pound longbow pretty well. The poundage is just right for him this year. It was a little heavy for him two years ago. I' d say for a 13 year old shooting longbow/recurve to look in the area of about 20 to 25 pounds. You could buy the bow with a few inches more then his actual draw length with either bow and let him grow into it with no problems.