In both Sun of Suns and Queen of Candesce by Karl Schroeder he describes "geared" cities which are a number of rings joined together so they turn like gears in a mechanism. They are described as a central ring with other rings round the outside resembling a flower, however it also says that a person could just step from one ring to another.

Six town wheels surrounded a seventh like the petals of a flower. Their rims touched and an elaborate scaffolding, shadowed behind them, indicated some fixed connection between them. When they turned, they would have turned in synchrony. You could step off one wheel and onto the rim of another—no cable cars for these people.

(Sun of Suns, chapter 17)

Surely if the rings are outside to outside like the "flower" configuration would require there's no way to step from one to the other as gravity would be pointing in opposite directions for each ring?

Have I misunderstood the descriptions or is there more to this?

  • I don't know the books you're mentioning, so I'll have to ask: Are those geared cities in space? Or why would you care about gravity? If they are on a planet, gravity shouldn't be a problem, as the rings would probably lie 'flat' on/above the ground. Commented Sep 17, 2013 at 11:03
  • I just googled and found some images, you're probably aware of (if not google "virga visualizations"). So we're talking about ringworlds here... Is there any mention of antigrav/artifical gravity in the books? Commented Sep 17, 2013 at 11:09
  • Virga's basically a giant balloon in space, thousands of miles across, with an artificial sun in the centre (and some smaller ones in outlying regions). There's no, or very little, normal gravity so the people living there use rings, sort of like tiny ringworlds, that they spin to generate gravity (really centrifugal force).
    – Alan
    Commented Sep 17, 2013 at 11:40

2 Answers 2


First off, let me say I didn't read the books (yet), but I just did some research and some hard thinking (also some crappy drawing) and came up with this:

I came across a layout describing the 'ying-yang' steps used to travel to/from the middle of a ringworld. I hope my sketch can explain it a bit:

enter image description here

With this step layout it should be possible to keep the strain of climbing with increasing/decreasing gravity relatively constant.

Those steps also lend themselves to my theory on how to cross from one ringworld to another. Let me show you another crappy sketch:

enter image description here

This sketch looks at the 'inside' of a ring, meaning the part between the inner surface and the outer surface. As you can see, by twisting the walkway, it should be possible to walk from one ringworld onto the other.

Possible caveats that came to mind:

  • It may be difficult to achieve that twist in the walkway, without people falling off. A handrail or something like that might be enough though.
  • I'm not sure how a body would behave on the exact change of direction of gravity. Maybe this won't work at all...
  • Synchronising steps to meet each other at exactly the right time might prove tricky. It would probably make more sense to connect the walkways to on another and not rotate them with the ringworlds themselves. This would make it possible to install stations at the inner surface, to 'cross over' onto the walkway. This all depends on the speed of the ringworlds rotation though.
  • I recommend you give the books a go as I think they're excellent. In them they use ying-yang steps to reach the centre of the rings, which is normally how they travel between rings: once you're in the centre there's no gravity so you can just fly where you want to go. The geared cities are described as just stepping from one ring to another, though, and maybe you're right and it's not just a literal step but a transfer through some sort of passage attached to the edge of the rings. I hadn't thought about that before.
    – Alan
    Commented Sep 17, 2013 at 11:55
  • I'm definitely planning on reading those books. Thanks for making me aware of them ^^ Commented Sep 17, 2013 at 11:58

The world of Sun of Suns written and created by Karl Schroeder is a complicated one and while it explains lots of things, it also leaves plenty to the imagination. It is not, however, a ringworld or halo construct. Think more on the lines of Niven's Integral Trees environment.

  • While the environment is quite sophisticated and indicates a very advanced society, the current citizens of the world are not the makers of this environment. Their technology is pre-computer, advanced mechanical with a few outlying technologies. I hesitate to say steampunk due to the advanced nature of the setting but it has been used to describe the tech level. Movement is done using small jet propelled aircraft, presumably clean burning and highly efficient. People have also been known to travel by airship or by flying personally with winged (unpowered) exosuits.

enter image description here

  • The environment Virga is essentially a fullerene gas bag around a star (possibly an artificial one in the center of the gas bag. The bag is two meters thick, rigid and encased in an icy glacier. There are asteroids and bodies of water floating inside of this gas bag in slow orbits around the tiny interior sun. The bag is filled with water vapor which keeps the temperature regulated and allows people to exist without freezing until they move away from the main sun.

  • The entire Virga region is listed at 5000 miles across and at in the center of this fullerene sphere is an artificial sun which provides a central mass for objects which float in Virga to orbit, very slowly. However, this sun does not provide much light and apparently not much heat either, because citizens of this world who choose not to live near that sun have pushed off and found other floating debris, large rocks and the like and anchor themselves to those rocks and create their own smaller suns for lighting and heat. (This is frowned upon but apparently not easy to stop.)

enter image description here

  • Move far away enough from the main sun and you reach an area of the Virga called Winter, where it is too cold to exist without an artificial sun. Resources also seem to be a bit scarce so fewer people choose to live out there, or it is simply harder to get by. On the diorama below, it shows suns and large land masses, with the giant diamond, I assume is the central sun/mass with the smaller jewels being land masses and artificial constructions.

enter image description here

  • The living areas vary in size from little more than towns which are rope and wooden constructions built on the inside of a wheel (imagine a bicycle wheel made of rope and wood and the people live in houses on the inside of the wheel). Cities grow in size when they can tether themselves to large asteroids and using fans and sails maintain their position around their drifting land mass. This image also shows geared cylinders connected to each other in the far right corner.

enter image description here

More complicated cities become cylinders made of metal (presumably mined from the floating asteroids). There can be multiple cylinders connected together in multiple arrangements, and since there is no gravity, once you move away from the centrifugal gravity, you are able to float/fly between rings, or cylinders.

There are potentially hundreds of townlets/cities depending on population, availability of resources and military capability. The town shown below was considered to be a town not wealthy enough to have its own sun. You can use it as a marker for scale.

enter image description here

All of these images are from Karl Schroeder's comic representation of his work at http://virgacomic.com/ where he and a talented group of writers, scripters and artists convert his vision into a comic format. His site also gives you a map and a description of how his world works.

enter image description here

  • A nice round-up of Virga, but it doesn't answer the question. The geared cylinders in the image aren't the geared cities described in the book, that city is Rush but the only geared city in Sun of Suns is in Leaf's Choir (is that the right name?) and as described bears no relation to the smaller town rings shown above. There are also geared rings in Lesser Spire in Queen of Candesce. I wasn't aware of the comic, I'll have to have a look at it.
    – Alan
    Commented Sep 17, 2013 at 12:54

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