its definitely a combination of things. He's new, this is his first bike since he was a kid. I'm fairly sure it is sized correctly. It is a GT Korakorum 2.0, i know I spelled that wrong. I have some spare rims that I wanted to try this, so I could figure out if its the wheels or what. I figured if I put some 26ers on there, then he rode it and had the same issues, we could eliminate that. He really just needs more time on his bike. I looked into doing those 96ers thinking that might be a happy medium, but it looks like that is frame based as well.