Velobiz: Mr Zedler, is it advisable and secure to repair damaged carbon parts of a bicycle?
From the ecological point of view it is advisable to repair carbon. But economically it typically makes only sense in the case of frames. For safety reasons, however, I also advise against repairing other components, such as handlebars, stems, forks, seatposts, saddles and cranks. These parts are not redundant and therefore much more sensitive. In this case, buying a new part is the better choice.
Velobiz: What should workshops do with customers attending them with carbon frames affected by impacts?
After an accident I always advise to replace the exposed components that were visibly subjected to force. Today, frames are usually very resistant, as far as no force was applied to one point. The feared “sudden death”, i.e. a term originating from the aerospace industry describing a component losing its structure all of a sudden and completely, is no longer an issue. We know that from many expert reports following accidents, but also from our test lab.
Frames can be checked after incidents to make sure that the structure has remained unaffected. With the analysis method pulse thermography as well as with the usual computer tomography damage can hardly be detected reliably. Tests are like repairs, handicraft methods are superior to automatic procedures. Static tests with different load cycles with noise and crack test under load and a comparison with well-known technical data from previous measurements of the frame type deliver the best results. This was performed by us in 1998 for the first time and today, more than 20 years later frames tested free by us in these times are still running.
Velobiz: There are a few specialists for carbon repair. How do manufacturers and retailers know they can trust these providers?
In the case of frames we are quite relaxed. The durability of carbon repairs has already been tested by us thoroughly in 2010, published at the road bike magazine TOUR and put up for discussion at conferences of the industry. To date it has not reached our ears that a component repaired failed afterwards. As we look at the situation the selection criterion is not the workmanship of the few specialised companies, but the duration of repair and the costs.
Nuernberger Zeitung, 2020/06/03
Frankfurter Rundschau.de, 2020/06/01