i bought a bike that was a little rough but was very cheap because of this. one of the first things i noticed was play in the front wheel. I didn't know what it was. At first I thought the quick release wasn't tight enough. But after inspecting it i saw the hub screw was loose. so i took off the wheel and removed that small plastic cap that meshes with the locknut and tightened it. That did the trick. I'm just wonder what would cause that screw to come loose? This was a mountain bike. Is that something that loosens normally oiver time? It was only a 2006 bike.