Especially in terms of product safety there are still some question marks. In his latest newsletter the expert Dirk Zedler raised various safety-relevant points of discussion where further improvement needs to be done. Consent is given to him by the manufacturers that are aware of the problems and assume their responsibilities.
In the past three years the bicycle expert Dirk Zedler of the Zedler Institute has conducted research together with engineering students and students from other faculties in view of developing handling options for pedelec manufacturers as to the riding stability of pedelecs. In Zedler’s opinion there are still some bicycles where the product quality has not yet achieved the required level. Therefore, from his point of view the manufacturers were requested to focus on improving the safety and quality of electric bicycles. Often e-bikes still turn out to be unsafe or even dangerous, either due to the design as such or to modifications on fully assembled bicycles.
For the expert the discussion is in full swing. There are still many open questions especially with regard to the legitimacy of replacing pedelec components. "There is no clear regulation available to date. That’s why in this point my basic findings from 20 years as expert at court take effect: "As long as there are no highest courts decisions made, the statements of lawyers and other specialists remain basically expressions of opinions and must therefore be handled with due caution. My advice regarding modifications on pedelecs is caution and proper proceeding from the side of the manufacturer as well as dealer," declares Zedler.
Accidents due to design must be avoided
Another subject is the wobble. It describes a deficiency which concerns some current designs. Various magazines, as well as among others the German product testers (Stiftung Warentest), had made public these deficiencies. The expert has already also been involved in a number of accidents "clearly due to design". A low step-through design, high additional loads, place for luggage, high handlebars, great comfort and a strong propulsion, that’s what is requested, but especially these constructions would favour the wobble or the oscillation. In this connections Zedler draws comparisons with the market of sports bikes, i.e. road and mountain bikes: Everyone who takes quality requirements serious is rewarded by the market as well as during the races. These quality requirements also include the fabrication of safer and more reliable bicycles by permanent further developments by a team of engineers. In doing so, the bicycles as well as the pedelecs always remain latest state-of-the-art-and-technology. "Eternally yesterday oriented people who refrained from undertaking research and development activities, in return have nearly sunk into insignificance", Zedler makes clear with regard to the world of sports.
Situation of the pedelec market is "unpromising"
For the expert the situation on the pedelec market is, however, unpromising. There subject of defective riding characteristics is justifiably boiling over. The sole attempt to close the jacket with one hand or to indicate a directional change correctly makes many pedelecs respond with a riding behaviour which can turn out to be dangerous. Poorly designed pedelecs respond to directional corrections at high speeds with reluctancy. In extreme cases riders can fall. According to Zedler, it is stated again and again that the overreaction or a rider arising from fear and panic can result in such accidents. Pedelecs weigh heavier than common bicycles and therefore need a better frame structure. In addition, the speed increases and actually untrained riders are confronted with a multitude of options. And whoever climbs a steep hill should be able to ride downhill safely.
Another simple possibility to minimize wobbling sees Zedler in the use of friction-type steering dampers. But this friction between fork and frame effectively blocks a good portion of the bicycle’s self-stabilisation which is absolutely necessary for this single-track vehicle. Therefore, this option has already been rejected many years ago in the case of motorcycles. Of weights in barends, equally known from the motorcycle sector, the expert is also critical: "They only suppress the symptoms and do not rectify the cause."
E-bikes are designed from scratcht
Therefore, the only alternative is to design a pedelec from scratch and to optimise it in many points. To overcome different phenomenons, a number of physical causes affecting each other mutually must be identified and eliminated. "Simple ’rucksack solutions’ – trekking bike plus motor – are therefore doomed to failure", warns Zedler. Especially to prevent wobbling more and more e-bike manufacturers build their e-bikes with the rechargeable battery in the centre of the frame. This measure clearly improves the centre of gravity and the riding characteristics of the e-bikes. Wobbling is a phenomenon which mainly concerns low step-through pedelecs with pannier rack battery. However, the choice of the pannier rack and the related position of the battery may have a positive effect on the wobbling. The negative wobbling effect must be taken into account already at an early stage in development. Solely by opting for the ideal geometry, the properly dimensioned tubes and the perfect positioning of the battery the phenomenon can be eliminated to the full. (…)
Author: Thomas Geisler