I'm 13 and pretty much all I will do is motocross. But, I also ride in the woods a little bit. I just don't really want to cut the foam out of my brand new bike, and do something just to make it shorter. Its not even about how tall it is. I'm scared what may happen when I wreck on it, cause I wreck alot! I crash so much that my little TTR even skinned me up pretty good. Plus, my parents would never let me get on a 125. I want a bike that I feel comfortable on and can use for a while. My dealer told me I was a good size for an 85 but I want something that I can grow into a little. I work for my dad on the farm so I have most of the money saved up, and the dealer told me that if I grow out of the 100 that I could trade it in on a 125 and pay the rest off. Also, I'm sure there are mods you can do the KX100. Heck you could get bigger pegs, taller seat, bar risers, then bore it out and you almost have yourself a KX125! Thats what I figure.