A method for quantifying impact loads from stone impact in mountain biking

High performance mountain bike frames nowadays are commonly built of carbon composites (CFRP), because of their excellent material properties allowing very high stiffness and strength at low weights. But this material has also disadvantages as it is sensitive to transversal impact loads. Impacts damage the material inside and can therefor affect the structural safety. As impact damages are often barely visible from the outside, they are very critical for structural parts like bike frames. A mountain bike frame suffers from different types of impacts like crashes and stone impacts. In order to evaluate the effect on structural integrity, the occurring impact energies have to be known. This paper describes a method for quantifying the impact load levels of stone impacts in order to evaluate the effect on the structural safety. Therefor the down tube of a mountain bike is shot using a high speed camera Casio Exilim EX FC 100 during biking. Impact events are identified in the videos and the impact energy is assessed, analyzing the stone geometry and its speed. Therefor a correlation between the two dimensional images of the stones and its mass was developed in an empiric approach. Using the above mentioned method, relevant impact energy levels and their frequency of occurrence are investigated.     «

High performance mountain bike frames nowadays are commonly built of carbon composites (CFRP), because of their excellent material properties allowing very high stiffness and strength at low weights. But this material has also disadvantages as it is sensitive to transversal impact loads. Impacts damage the material inside and can therefor affect the structural safety. As impact damages are often barely visible from the outside, they are very critical for structural parts like bike frames. A moun...     »