The study estimates the fatigue life of a bicycle frame after fatigue failure due to the operational loads. Mechanical properties were determined for a tubular frame made of 25CrMo4 steel. High-cycle fatigue tests were carried out for mini-specimens taken from the location of fatigue failure (joint material) and the base material. The experimental data were compared using a normal distribution for the S-N area and an analysis of the slopes for linear regressions for two data populations. The bicycle frame was evaluated using a fatigue strength approach and nominal stress values. The conditions of the analysis conformed to the safety requirements laid down in the international ISO 4210 standard. The stress was calculated using a finite element model consisting of the surface elements. The highest stress points were selected to compare different fatigue evaluations. The FEA and material data results were compared using a probabilistic Weibull model (P-S-N curve). A mean stress effect was allowed for using the Walker model. The highly stressed volume model and weakest link theory model were used to analyse the size effect. The fatigue life was estimated for the maximum stress determined using FEA. The maximum stress point corresponds to the fatigue failure location on the bicycle frame. The fatigue life at 10% failure probability is below the value recommended in accordance with ISO 4210. A key factor affecting the results is the operating conditions, including the angle of force applied to the bicycle pedals.

该研究估计了由于工作负荷导致的疲劳失效后自行车车架的疲劳寿命。确定了由25CrMo4钢制成的管状框架的机械性能。从疲劳破坏的位置（接头材料）和基础材料中抽取了一些小样本进行了高周疲劳测试。使用SN的正态分布比较实验数据面积和两个数据总体线性回归的斜率分析。使用疲劳强度方法和标称应力值评估了自行车车架。分析条件符合国际ISO 4210标准中规定的安全要求。使用由表面元素组成的有限元模型计算应力。选择最高应力点以比较不同的疲劳评估。有限元分析和材料数据结果使用概率威布尔模型（PSN曲线）。使用Walker模型时，允许平均应力效果。使用高应力体积模型和最薄弱环节理论模型来分析尺寸效应。对于使用FEA确定的最大应力，估计了疲劳寿命。最大应力点对应于自行车车架上的疲劳破坏位置。故障概率为10％时的疲劳寿命低于ISO 4210推荐的值。影响结果的关键因素是工作条件，包括施加到自行车踏板上的作用力角度。