Bicycle sprocket drive apparatus with elliptical pedal path

Abstract

An improved-efficiency, pedal-operated drive mechanism for a bicycle employing an elliptical sprocket used in association with a planetary-type gear drive for providing an elliptical path of travel of the bicycle pedals. The gear arrangement is disposed in a circular frame mounted from the conventional bicycle frame having secured therein, in a stationary position, an internally-toothed ring gear. The planetary-type drive also includes a pair of rotatable pinion gears diametrically meshed with the ring gear and supported in a bearing housing within the frame on respective pedal axles which are each secured to a pedal arm. The motion of the pedals is along an elliptical locus as the pinion gears individually but synchronously rotate in the fixed ring gear. The sprocket which is preferably of elliptical shape is secured to the housing and rotates therewith driving the bicycle with an improved efficiency on the order of 25 percent or more in comparison to the conventional circular drive system.

Dependencies are inferred from the claim text.