On Jan 13, 3:16 am, " wrote:
http://www.google.com/patents?id=Pj5HAAAAEBAJ

What happens here?

As drawn, nothing happens. There's no mechanism to compensate for the
varying chain length, and the chains are either going to bind or
skip. Later proponents of elliptical chain rings have realized that;
a) The sprockets need not also be elliptical, b) There does not need
to be two chains, and c) There needs to be chain slack and some kind
of spring loaded tensioner.