Geometric Analysis and Maintenance of a Sprocket

Abstract

This thesis investigates the geometric deterioration of a three-gear bicycle sprocket assembly with 28, 38, and 48 teeth. It uses reverse engineering and 3D laser scanning to capture the worn sprockets, then reconstructs their CAD models using Geomagic Design and Siemens NX. Restored reference models were created by adding 0.1 mm to the tooth profiles, allowing comparison between the worn and estimated unworn geometries. The analysis showed that the greatest wear occurred around the tooth perimeter, with the large gear showing heavy continuous wear and the medium gear showing the most irregular deformation. The main wear mechanisms identified were abrasive and fatigue wear, with possible adhesive and corrosive effects depending on lubrication and operating conditions. Based on these findings, the thesis proposes preventive, condition-based, and predictive maintenance actions such as cleaning, lubrication, tightening checks, visual inspection, and diagnostic measurements.