the big wheel is a collection of four scales.  The major scale and the melodic minor scale are fully represented.  In fact, the big wheel builds off of the little wheel.  on to the little wheel we attach three extra modes: the second and seventh mode of the Neapolitan major scale as well as the seventh mode of the Neapolitan minor scale.

When put together, all of these modes can be seen to show a sort of “circle of fifths” structure on the outside with five modes that bisected down the middle.  Closer investigation will show that in fact these are two loops within the space.  These two loops our topological and reflect the structure and the nature of the space and do not necessarily have musical significance.  On the other hand, the major and melodic minor scales are fully represented within this construction and thus this can be used as a basis by which to extend either scale.