As I said at Flickr, a little explanation about the technical construction of the wheel :
The base is not complicated: it is a cross formed of round plates and round bricks 1 x 1, and assembled on a cross (Technic, Axle Hub Connector with 4 Bars)
The circle of the wheel, it is composed of four parts: "Plate, Modified 1 x 1 with Clip Light - Thick Ring" of both sides, a "Plate 1 x 6," the "light clip" in opposition relative to each other, in which comes to slide "Stop with a Bar 6L Ring", and "tile 1 x 4" between the two "Light clip" to finish.
This technique allows to adjust the angle variations and thus to define different angles. Therefore, any constraint on the inter-axis.
(Sorry for my english )