Determining the stress distribution in a bicycle crank under in-service loads

Abstract

New techniques have been introduced in the design process of most of the components of a bicycle. One of the main purposes of this introduction is trying to achieve the best weight/rigidity relation. However, all these advances have to take into account the security of the rider. Unexpected failures of some components such as stem, handlebar, or cranks, can cause serious injuries to cyclists and have to be prevented. Standard EN 14781:2006 establishes the safety and performance requirements that every bicycle and every component must fit from the point of view of fatigue failure. In this work, several bicycles cranks will be experimentally tested under the loading conditions of the reference standard. The stresses on the critical points will be analyzed to determine the influence of any variation in the test conditions. According to obtained data, several changes in the conditions of the standard will be proposed. Also, loading tolerance values for the test will be suggested, because they are not established in the standard.