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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Lightweight construction requires a rethinking in the workshop
Explaining important technical terms with easy to understand examples was a central part of the lecture held by bike expert Dirk Zedler. He explained terms like stiffness, which indicates the resistance to bending, or strength, which is a measurement for the resistance to failure. These term may be quite common. But far less people know about the elongation at fracture. This measurement indicateds the deflection of a component before it breaks.
With an easy to understand example for this, Zedler jumped right into the subject: When having a rear-end-collision with a bike, a steel fork can bend so much that the wheel stand is reduced by several hand's breadths. A carbon fork breaks without any permanent deflection. Afterwards, both parts can be put together to form the original fork. These examples make it clear why such components have to be examined very carefully after a crash. In case of doubt, it is advisable to ask the manufacturer for advice or to replace the component, the customer has to be informed in any case! Damaged components do not necessarily have to be deflected. Also aluminium or magnesium are more problematic than steel because of their low elongation at fracture.
Time and again, there are bike components which have not been fully developed or with which price or design has been more important than functionality. Particularly when it comes to lightweight components dealers have to sell adequately and assemble expertly. When somebody weighing 90 kilograms wants to buy an ultra-light carbon seat post for his hardtail, alarm bells have to ring.
Assembling a bike with exklusive lightweight parts requires a lot of knowledge and care. Often, it is not piece parts causing problems. It is unlucky combinations, and concentrations of mistakes which cause them. You may think it is his own fault if somebody puts an aheadset-stem on a fork steering column with a thread. But Dirk Zedler already's had to deal with such cases.
Is it therefore any wonder that mistakes are even more likely to be made when assembling bikes which are on the technical level of formula-1-cars? It is, for example, a mortal sin to grease the clamping zone of carbon components. Instead, the friction between the parts has to be increased. This is possible with a combination of ahead-stem/carbon fork steering column with sandblasted ,ie, harshened nuts. Insert nuts in carbon frames, however, have to be greased in order to avoid corrosion and to make future disassembly easier.
Further, not every high-tech material is fit for every use. Stainless bolts do not permanently resist to bending and are therefore not to be used for clamping handlebars, stem or saddle. Or titanium which is far more elastic than steel. Due to this, titanium frames are comfortable to ride on and therefore highly esteemed. But when titanium bolts are used for swellingly stressed combinations like the saddle clamp, this is, plainly put, wrong. The connection may come loose.
This shows that assembling exklusive bikes requires a lot of knowledge and experience.
RadMarkt.de 2019/12/10 and 1/2020