MANUFACTURING METHOD FOR BICYCLE CRANK ARM, BICYCLE CRANK ARM WHICH IS MANUFACTURED WITH THE MANUFACTURING METHOD

摘要

PURPOSE: A manufacturing method of a crank arm for bicycle and a bicycle crank arm manufactured by the same are provided to implement light product by making the inside of the crank arm hollow. CONSTITUTION: A metal plate is extruded(S2). A crank arm base has a crank arm load area having a hollow part in a longitudinal direction. One area of a processing part is cut from the crank arm base along the longitudinal direction of the hollow part(S3). The crank arm load area of the cut crank arm base is bent based on a cut area(S4). Both end areas of the crank arm load area is pressed in order to close the hollow part at the bent crank arm base(S5).