A Novel Model for Bicycle Drivetrain Efficiency

Abstract

This study introduces a new model for bicycle drivetrain efficiency, termed the “DC” (Dowd-Cavanaugh) model. This model is a comprehensive approach for characterizing cycling drivetrain efficiency across varying conditions—a critical factor in optimizing the performance of bicycles in competitive, recreational, and transportation contexts. A specialized testing rig was developed to measure drivetrain efficiency under different simulated riding conditions, with a particular focus on the performance of chains using various lubricants over varied torque and RPM conditions. Analysis revealed a linear relationship (R^2 > 0.999) between efficiency and the DC metric, defined as DC_metric = RPM^0.3/Torque, providing a comprehensive framework for predicting drivetrain efficiency. Through regression analysis, the slope and intercept of this linear relationship were employed as all-encompassing parameters characterizing drivetrain performance, facilitating targeted lubricant selection based on specific cycling scenarios. The DC model establishes a robust framework for advancing both practical applications and scientific understanding of cycling drivetrain efficiency. The broad applicability of the DC model in analyzing efficiency across different situations offers substantial opportunities for optimizing drivetrain performance, especially in aligning mechanical and physiological efficiencies for prolonged, lower power outputs.