It tilts purely by tensioning the quill stems where you would normally have a handlebar. They are quill stems but are very beefy built. The Frame itself is chromed or highly polished steel and has a bit of weight to it, especially once assembled with stems, wheel etc. This is what would stop it bouncing on its own. The quill bolts are what's used for tensioning are also greased where they mount to allow them to move. The design of the frame and the tubing it mounts into on the bike means that it cannot move for and aft and the tensioning is only backed off to allow it to move up and down and then backed off again so it can fold up when not in use. It's never meant to be so loose there is no tension as any rattling about will snap the bolts or stem.
It is rated to 250lbs or 113 kg so pretty substantial. That's a big dog or a lotta cheese
Jamie
It is rated to 250lbs or 113 kg so pretty substantial. That's a big dog or a lotta cheese

Jamie