[John W]

Chi,

I don't think that's the way it is done.

If you look in the pics you can see the actual wheel rim, not an insert inside it.
Both bikes are done differently. One has a central spine in the rim with a red hoop bolted to the frame. The hoop acts as the wheel spindle in your description.

The other bike has the hoop on the side of the wheel (between sprocket and wheel to be more accurate) so it looks like there is nothing at all inside the wheel.

Very clever engineering. Looking through the other bikes they have some trully stunning bikes. As Iconic says though, you have to wonder just how strong the frames really are. I assume they simply use large section tubing and over engineer everything.