Contributions of rider-induced loads to bicycle frame stress

Abstract

Presented in this paper is a new method for design analysis of bicycle frames. The new method relies on measurements of rider induced loading to perform a stress analysis of a bicycle frame. The vehicle for the stress analysis is ANSYS, a commercially available finite element code. Through application of individual measured loads, the method examines the corresponding nodes of maximum stress. Polar plots are developed to illustrate the variation of stress as a function of crank arm angle. Polar plots are also developed for the nodes experiencing the maximum total stress. Such a procedure enables the contribution of individual measured loads to the maximum stress to be ascertained. With this information, not only are the important loads for design analysis identified, but also the structural members of relative high and low stress are determined. Accordingly, these results have application to the detailed design of individual structural members. To illustrate the new method, stress analysis of an aluminum frame is undertaken. The loading data are derived from an earlier study by the authors where significant seat, handlebar, and pedal loads were measured together with absolute pedal position. The loading data simulate that of steady-state cycling over flat terrain at about 9 m/s (20 mile/hr). The node of maximum total stress under steady-state loading is found to be the intersection of the top and seat tubes. Inasmuch as frames typically fail in the area of the bottom bracket (i.e., intersection of down and seat tubes), this result contradicts experience. This contradiction is explained by observing that the alternating stress/mean stress ratio is significantly greater for the bottom bracket area.

The Steel Bicycle Project: Bringing Together Tube Manufacturers, Frame Builders, and Engineers through Sports Engineering

“…Computer simulations have been used since the 1980s [3][4][5][6] (Figure 2) and can be used to complement experimental testing to gain a fuller understanding of bicycle behaviour. Previously published work in this area has aimed to help understand how specific frames might behave under known load conditions [3][4][5][6], how the frame geometry (in the form of tube lengths and angles, and tube section profiles) can influence the stiffness of the frame or parts of the frame [3,[7][8][9], and how optimisation techniques can be used on frame geometry [7,10]. One aim in this theme is to help frame builders assess how design changes can affect the mechanical behaviour of their frame designs relative to benchmark designs, but also, in absolute terms, by validating model outputs using experimentation.…”

Influence of Electrically Powered Pedal Assistance on User-Induced Cycling Loads and Muscle Activity during Cycling

“…Forces and moments are measured in the three dimensions and related to the pedal position within the pedal cycle. User-induced loads are useful to design bicycle frames and components [4] and to derive lower limb joint loading at the knees, hips and ankles by inverse dynamics [5]. Joint loading patterns are utilized to evaluate cycling for rehabilitation [6], to predict overuse joint injuries [7], to analyze muscle function [8] and to optimize cycling performance [9].…”

Design improvement and fatigue analysis for a bicycle handlebar stem system using uniform design method and genetic algorithm

“…Some studies use finite element analysis of the bicycle frame system to determine the static stress for a bicycle frame. 1–3 The deformation and stress in a three-dimensional (3D) bicycle model are the subjects of several studies. 4–7 Covill et al.…”