Well the curvature of the orbit at the earth <-> sun distance is minimal. So you have to hit a decent fraction of the speed of light to create that centrifugal

Well the curvature of the orbit at the earth <-> sun distance is minimal. So you have to hit a decent fraction of the speed of light to create that centrifugal force to replace the earth normal 1G. Those incredible speeds mean that all of ring world is under 1G of force, which creates incredible tension. What I don't know is if the sun was 1/16th as bright and physically smaller if that would bring the ring into the realm of physically possible.