SAZbike 15/2011

Bicycle expert Dirk Zedler criticises: Foundation impedes progress of safety by non-transparency

SAZbike spoke with bicycle expert Dirk Zedler (managing director of Zedler - Institut für Fahrradtechnik und –Sicherheit) about the latest e-bike test of the German foundation for comparative testing (Stiftung Warentest). What the graduate engineer claims most is above all the non-transparency of test criteria, which are neither displayed to the manufacturers nor to the public. Furthermore, Zedler criticises the editorial realization of the test. However, the expert also reminds the manufacturers of their responsibility: The results of the brake tests, for example, are identic to his own findings, and the test hardness for monotube frames is another point that is approved by Zedler.

SAZbike: Mr Zedler, what’s your opinion about the latest e-bike test of Stiftung Warentest?

Dirk Zedler: Basically, I highly appreciate tests being carried out by neutral, independent parties. To date, tests have mainly been carried out by Extra Energy e.V.

Their testings and used test equipment are absolutely groundbreaking, the publications for final consumers generated by them are, however, all in all rather thin. The results of the EMC-tests, the riding behaviour and the operational strength were nearly covered by a veil of silence. Although the discovered problems are discussed with the manufacturers, the final consumer is left uninformed. In these points the club who has the declared aim to promote electric mobility can apparently not overcome their own fears. The only just launched popular journals mostly limit themselves to test runs, serious testings are not performed. Therefore, it’s like a slap in the face for the sector when harsh judgements are made.

In my opinion, the problem with this test is clearly the editorial realization. Instead of starting with positive facts, it is titled: „Rahmen bricht, Bremsen versagen“ (Frame breaks, brakes fail). The media descended on the subject as enthousiastic as a few weeks ago on the examinations of the UGV/GDV (see SAZbike no. 6, 2011/04/18). After all, that counteracts in my opinion the reasonable mobility trend especially in urban areas.

? What can you tell us about the test criteria?

! The test criteria applied by Stiftung Warentest are documented in a very detailed requirements specification. This draft is discussed in an advisory committee attended by consumer representatives (ADFC, ADAC, experts), dealers, manufacturers and test institutes. Following this discussion it is decided internally by Stiftung Warentest what to actually test. All in all the test scope is extensive and reasonable. The strict criteria, e.g. for the sensitive operational strength tests are, however, not published in detail. In so far, it is impossible to make a final decision about these points.

? During the Vivelo-Conference last year test manager Holger Brackemann invited you to visit Stiftung Warentest. What has actually come forth?

! The disclosure of the test criteria promised in front of the audience has not been realized to date. The only new thing for me was therefore the attendance of the advisory committee’s meeting in Berlin. Now I know more about the procedure until this point. As regards the actual tests and in particular the comparison of the results with realistic breakages in practice which is at least of identic importance, I’m still groping in the dark.

? What are the concrete points that you criticise about the testing methods of Stiftung Warentest?

! The major deficiency is, in principle, that some of the test criteria are not disclosed. For this reason experts from the sector are not even able to discuss about them. For the manufacturers that means that they can’t test according to these criteria, to improve their products in this regard. Due to the undisclosed test requirements it is more difficult to make comparisons with realistic values. To conclude, my major criticism is that this procedure also impedes progress and the growth of bicycle safety.

? Are these deficiencies also applicable to the latest test?

! There are a few details that I don’t like with the latest test. The video on the StiWa-website shortly shows the brake test. At least the zoomed in brake pad is improperly adjusted. It doesn’t hit the brake surface of the rim entirely, but projects to the bottom, i.e. towards the hub. That means, that full braking performance cannot be achieved. The brake lever moved from the test stand also has an excessive travel. It cannot be clarified whether this is due to improper adjustment or to a brake with poor braking effects.

The second point is the damage which was most probably caused by the drum test stand. According to my experience, broken sprockets and chainrings haven’t occurred in practice on bicycles of the past years. The test hardness resulting thereof makes the relevance of the test results, such as torn chains, broken front lamp holders and pannier racks appear questionable.

? In which points do you agree?

! Reading through the article without emotions, you come across a number of findings that you can agree with. In spite of the aforementioned objections, the results for the brakes mainly comply with my experiences with brakes in general. Manufacturers allowing heavy weights must unconditionally come up to what they have specified.
I have neither a problem with frames combined with front motors being tested hard, all the more in the case of monotube frames. If such a frame fails, the rider falls. In my function as expert I have dealt with lots of expert’s reports about monotube frames of normal city bikes in the past years; with the electric motors the loads will increase significantly.

? What are the consequences the test will have for the perception of e-bikes in the public?

! It is not so much the test results, which will lead the very much welcomed pedelec and e-bike wave into its hardest time, but the article in the “Test” magazine and what the other media have made of it. The most different interest groups are more and more trying to bear down on it to get the young und successful little plant under their testing and regulation authority. It’s all about possible big businesses. If the bicycle sector will not work hard on it to find a common line, they will sooner or later be likely to loose control of this issue. And this possibly with harmful consequences for the bicycle as a whole.

Consumers who don’t have themselves put off by headlines and will read through the article in the "Test" magazine, will quickly find out that there are also many positive aspects and that a good pedelec is due to cost its money. An advantage for manufacturers and dealers.

Mr Zedler, thanks a lot for the interview.

The interview was held by Alexander Schmitz.

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