Loads, Stresses, and deflections in Bicycle Frames

Abstract

A bicycle frame has been analysed as a three-dimensional framework and stresses and deflections predicted using a finite element computer program. Theoretical results for simple loading case were compared with strain gauge measurements in laboratory tests. More complex loading cases representing common cycle racing situations were analysed. The largest stresses in the frame were bending stresses. Stresses in the region of 300—400 MN/m2 were predicted in the down tube and right chain stay during starting and stresses of about 250 MN/m2 at the front of the top tube and down tube during severe braking.

On the Effects of Tube Butting on the Structural Performance of Steel Bicycle Frames

“…The change in bending stiffness was limited to a maximum of 25.7% (whole frame), while the change in torsional stiffness was limited to only 27.0% (single joint). Overall, the reduction in these stiffness values was in line with the reduction in second moment of area, I, since the bending moment in these load cases was linear along the tube length, which was also noted in [2]. Similarly for the out of plane/torsion load cases, the constant 1 N · m torque along the length of the tube resulted in an overall reduction in stiffness that was in line with the changes in the polar second moment of area, J.…”

“…This model was used previously in [17], and was extended in this study to allow for tube butting profiles to be accounted for in the top tube, downtube and seat tube and again a mesh refinement was applied until the results converged within 98% of a target accuracy in the fillet area [25]. The frame material properties were the same as in 2.1 above, and the load cases were based on those presented in [2,3,17] for the in-plane bending due to a road bump at the front wheel, and out of plane/torsion due to climbing out of the saddle. These load cases are depicted in the free body diagrams in Figure 1c,d.…”

“…While in this time it has been possible for large scale manufacturers to customise butted tubing profiles for mass produced bicycles, in recent years, customised tubing profiles have become more accessible to small scale frame builders for specialist one-off frame projects [1]. To complement the progress made in materials and manufacturing technologies, the use of numerical simulations is also becoming more common amongst bicycle designers to analyse frame behavior and, where possible, assist in designing more lightweight and fit for purpose bicycles [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18]. Previous studies have shown how finite element analysis (FEA) can be used to support designers in the selection of individual tubes to tune the stiffness and strength behaviour of frames [1,13,15,17,19].…”

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.…”

Conceptual design of bicycle frames by multiobjective shape annealing

“…For each case, loads are imposed at the three application points shown in Figure 6. Because the topology and geometry of the system are changed during the optimization process, the loads at these points are varied to ensure that equivalent conditions are maintained for all designs [33,34]. Table III gives details of the three loading cases used.…”