A quick calculation for 1g spin gravity at a leisurely 1 round per 20min gives a radius of 360km.
Assume, we find a strong enough material for lightweight cables, what are the challenges for building a Bola-style habitat (i.e. two stations rotating around a common center of mass)?
- Is the large radius a problem on "habitable" earth orbits (tidal forces)?
- Is it difficult to maintain the common center of mass of such a large (but comparatively lightweight) structure?
- Is it difficult to start the desired rotation?
Which radius is practically possible?