Everything’s fine?
We could actually relax and lean back. The companies that we can count as our customers were among the first in those areas they have relied upon us. The test winner has his products tested in our laboratory.
Nevertheless, the behaviour of Stiftung Warentest (German foundation for comparative testing) and ADAC (General German Automobile Association) is absolutely inacceptable.
The results of the latest pedelec tests are partly alarming. Manufacturers just like test laboratories are in the dark when it comes to comprehend the results. A conceivable option is to simply sit the issue out.
What however, if the results of Stiftung Warentest and ADAC are correct? What, if many pedelecs are actually so dangerous?
Due to several factors, such as the higher weight and the higher speed, pedelecs are undoubtedly exposed to higher loads than common trekking bikes. At present, most of the pedelecs have only recently been put on the market; due to the short useful life, fatigue damage, also referred to as endurance failures, may happen in future.
The procedure
Figurehead and hook for the collective bashing of the sector are operational strength tests and EMC tests. For years StiWa (German Foundation for comparative product testing) has been boasting high the service life testing of bicycles by means of operational load simulations, i.e. the highest evolution level of fatigue tests. Based on real data entries conducted by order of StiWa, the Berlin product testers even dare indicating a kilometre performance of 20,000 km for the test results.
Breakages occurring in the course of such a short running performance would be a disaster indeed. This leads us to the following questions:
Is the test actually realistic or are a few products so weak?
Were real data entered only or was a benchmarking process conducted with reliable and weak products before the tests?
Therefore: Is the test valid?
The results
Even without knowing the test criteria and test conditions in detail, some of the results in the test reports call for an explanation. Although there is only one manufacturer of hydraulic rim brakes (Magura HS), the braking performance in the test field vary from “very good” to only “adequate”. The only thinkable causes could be brake levers of different lengths and additionally mounted brakeboosters. Nevertheless: With the constant aluminium rims with overly milled rim sides and always identical brakes, there is no reason to expect such a great difference.
The EMC results of the Bosch system vary from ”satisfactory” to “adequate”. Light needs to be shed on the great difference, as the complete system from Bosch comprising the battery, the drive, the wiring harness and the HMI is not variable, unlike the system of a few competitors. The described switching off due to external disturbances is something we do not know from our day-to-day operations.
Last example for the necessary transparency is the top-rated processing quality of the very low-priced Fischer pedelec. The question why this pedelec was rated “very good”, whereas the models from Stevens, Kettler, Hercules, Victory or KTM only got a “satisfactory”, is certainly not only interesting to the quality managers of the manufacturers.
The weaknesses
On the one hand StiWa and ADAC render a harsh judgement, on the other hand too little attention is given to one actually critical issue which concerns lots of current pedelecs. Especially lots of low-step-through models show a dangerously instable riding behaviour. Due to the not yet fully developed frame structures and a modified centre of gravity, the bicycles are prone to rocking. To indicate a change in direction by hand already turns into a risk.
Conclusion
More than three years ago head of StiWa testing, Dr. Holger Brackemann, making currently a name for himself by bashing the bicycle sector, had promised more transparency for the criteria and a better cooperation during the panel discussion at the vivavelo conference in Berlin. This promise has, however, not been kept by StiWa to date.
Both StiWa and ADAC render a harsh judgement while standing on thin ice in what they state.
The refusal to make the test criteria transparent leads to the fact that committed companies can test according to the probably latest state-of-the-art in testing technology. By the thought not to be able to fulfil the standard anyway, companies that are not yet performing tests according to the latest state-of-the-art testing technology, will not at all be motivated to improve the product durability and thus the safety.
But only, when StiWa and ADAC will stop stonewalling, the product testers will fulfil their very own mission. We are prepared to the exchange.
Dirk Zedler, graduate engineer
Officially appointed and sworn expert for bicycles (CCI Stuttgart)
Managing director Zedler – Institut für Fahrradtechnik und -Sicherheit GmbH
