Riding Performance and Design of Elliptical-Eccentric Sprockets Chain System for Bicycles

摘要

The use of elliptical front sprocket can enhance the riding performance of cyclists, but it would cause chain slack during operating, or lead to chain drop. A novel concept is proposed to reduce the chain slack, by introducing the eccentricity of the rear sprocket, and improve the riding performance. The purpose of this study is to analyse and evaluate the effectiveness of the system. The geometric, kinematic and mechanic models for the elliptical-eccentric sprockets system are developed, and the criteria for evaluation have been proposed. Computer programs are used for finding the elliptical ratio and eccentricity of the system, and then, the riding performance compared to the traditional system would also be investigated. The driving torque and driving power at each joint will be used as the index for the riding performance. This study could be applied in practice and promote the design and research on the non-circular sprockets for bicycles.