What do a broken bike component and a cut down tree have in common? Of course, both are dead. But also their cut surface, ie, their fracture plane, look similar. And just like natural history experts can tell the tree’s age and growth per year from its annual rings, material experts cann tell from the rings in the material why the construction failed. Often, it is the fault of only very tiny defects that time takes its toll too fiercely on road bike components. The cunning thing about such so-called endurance breaks is that the breach getting bigger can hardly be seen from the outside. At some point, the component becomes so instable that it cannot fulfil its task anymore and breaks all of a sudden.
Comment
Modern road bikes are lightweight constructions from the constructional point of view and are usually used quite intensely. Both factors make it seem careless that some manufacturers did not test their products at all or not sufficiently.
Everyday experience shows enough cases in which certain parts or a whole series got bad marks. The companies concerned know about it; the parts have often been improved in the course of the running production or with the succeeding model at the latest. Nevertheless, companies only very rarely recall dangerous products. This is irresponsible. Manufacturers should become active before crashes with severe consequences happen. This is also demanded by law in the context of product liability.
In order to avoid accidents caused by manufacturing defects, only material should be put on the market whose lifespan had been tested according to its purpose. Furthermore, parts should get some kind of "best before" stamp.
Author: certified engineer Dirk Zedler, bike expert, Ludwigsburg
