BIKE: Carbon is a wonderful material for bikes: stiff, lightweight and when bought second hand just affordable. But what about safety in the case of second hand components, such as handlebars, seat posts or cranks?
Zedler: The crux of carbon is that the material comes out of a fall or accident without a deformation, even if it had been exposed to overload. This makes a judgement from the outside almost impossible. As the BIKE handlebar test (5/14) has shown, there are wide differences in the durability and in particular in the accident tolerance of carbon. In the case of second hand handlebars, seat posts and cranks you therefore run a high risk, if you don’t know the history of the components.
What can I do to minimize the risk, where are the limits of wear marks or age?
The ageing process of carbon is not an issue, damaging incidents such as failed jumps or falls are much more critical. In theory, you can tell previous damage incidents from the handlebar grips, the pedals or the saddle. But these components are often replaced before the sale to achieve a higher price. The only possibility for those who want to be on the safe side is to replace the load bearing components.
Carbon frames, no matter whether full suspension or hard tail, have certainly the biggest second hand saving potential. These are, however, yet another issue. How can I avoid buying a ticking time bomb?
From the experience the all-clear can be given for most frames. In the case of the well-designed frames of the leading manufacturers the sudden death is no longer an issue. In addition, the risk is a little lower, as the tubes provide support to one another. Before buying it is worth having a critical look at the exposed components. If the pedals, grips and saddles are not made available by the seller, or if they are suspiciously new, I would advise against buying. The condition of the wheels also tells something about the history of the second hand bike. Another indicator is the paint. On a very clean frame you can either see cracks in the critical areas or feel them with a soft rag by stroking the tubes.
Are there any possibilities to have a frame professionally examined for defects/shortcomings?
The often cited X-raying, just like other fluoroscopy procedures do not produce real results. As carbon is manufactured by hand there are forcibly deviations in the production and it is virtually impossible to distinguish uncritical manufacturing deficiencies from possible damages. For a reliable statement the condition as new should be documented. But this is unfortunately never the case.
Some few manufacturers including our team at the Zedler institute test carbon frames with an extended stiffness test procedure in the laboratory. But this requires a lot of experience and equipment. Costs: from 500 € on.