I have two Ecotric 20 inch folders. On one of them, I have noticed that the front fork seems to shift a bit on hard braking, as if applying the brake stops the wheel and fork but reveals a slight looseness as the main frame catches up to the fork. The other bike demonstrates no movement or looseness on similar braking. At first I thought one of the wheel might not be sitting right in the dropout, but they seem snug, and after repeatedly applying both brakes, rear only, front only while walking the bike, I think I have isolated the movement to the front fork. I tightened the allen bolt under the folding handlebar, and thought it made a little difference, but the tightening didn't eliminate the behavior. I put both bikes together myself, and don't remember doing anything different on either bike in the process. It is only a slight movement on braking, not dramatic, but I would like to eliminate it nonetheless. Sorry in advance for the vague description - if I actually knew the source of the problem I am sure I could describe it better. Any suggestion on things I should check or adjust will be most welcome.