I limit the travel on mine with the cable length - to keep the chain from going off into the spokes.

If the cable fails - well - the thing is so stiff, crusty, cranky, and lame, I doubt it can travel much on it's own. But it sure looks cool, and it's period correct, and that's what counts. No one in their right mind, back in the day, would put any fancy Italian crap on a Sports or a low end racer.