Elliptical Bike Crank

The idea was that the large radius of the chainwheel would drive the chain when the cranks are horizontal and the small radius would pull the chain when the cranks are vertical.

Elliptical bike crank.

The 11s is the fastest most versatile and most technologically advanced streetstrider ever built. To clear up any confusion the chainring does not produce more power. Featuring a hybrid elliptical motion the compact stride bike targets a variety of muscle groups for a time efficient full body workout without the impact. With its combination of quality and performance at a great price the elliptigo arc 8 quickly became the top selling stand up bike in the world.

That shimano manufactured an elliptical chainring in the 1980s called the biopace and aside from a few love letters the component was generally panned for causing undue stress on the knees. Simply put the oval or elliptical chainring helps maximize the power you personally put out when you are at an optimal part of your pedal stroke to lay it down and allow the bike to be a little easier to pedal when you are in the non optimal part of your pedal stroke.