In our daily work as we deal with bicycle safety, technology and user manuals we come across lots of safety risks. The most frequent ones are published in articles of the leading German special-interest magazines TOUR – Europas Rennrad-Magazin Nr. 1, BIKE – Das Mountainbike Magazin Europas Nr. 1 and E-Bike – Das Pedelec-Magazin to make this information important for the sector accessible to a wider public.
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I read Dirk Zedler’s interview on the safety of used bicycles in your August issue with a special interest. Because after many years without accident, the luck has finally abandoned me in this respect. Due to a sudden full braking of a car driver, I bumped into the rear of the car at relatively high speed. From the outside the bicycle does not show any defects, the frame (aluminium) was measured and is not distorted. It is out of the question that I have to replace the carbon fork in the front for safety reasons. My question is about the handlebar and the stem, both made of aluminium. My Pinarello Galileo originates from 2008. As the new fork will cost already quite a little, I’m asking myself whether the replacement of handlebar and stem is necessary at all. If these components were damaged, wouldn’t that be evident? Or is there the risk that the aluminium will break suddenly during the ride?
Reply by Dirk Zedler, TOUR technology expert and bicycle expert
First of all, I hope you are all right again after your accident. And as to the components: You have to differentiate between damage caused by overload and damage caused by more or less evenly applied loads. The latter type is called fatigue fracture; it may happen suddenly at any time when no one would expect it. In this connection, all loads acting on a bicycle component during its service life are of importance, because the material has a "memory". Apart from the usual loads arising during the ride, such as the riding over cobbled streets, potholes or manhole covers, the interaction of the rider is also decisive for many components like the stem. Riding out of the saddle, for example, leads to an enormous load acting on handlebar and stem. As a result, the components are subject to fatigue and components made of aluminium tend to fail after a certain time. The actual date of failure depends on construction, manufacture and maintenance as well as use. In a case like yours, I would recommend that you play safe and replace the components, not least due to my long-standing experience as loss adjuster. When you bump into a car ahead of you, you lean heavily on handlebar and stem. This load is definitely higher than the usual one. Even if the components are not bent, the material "memorizes" this extreme load and can fail at any time.