He would deal with a lot of accidents in his practise as an expert which were due to the design: "On many pedelecs already the attempt to indicate a change in the direction of riding is answered with a riding behaviour that can turn out to be dangerous", states Zedler.
"Any readjustment of the direction of motion by the rider when riding downhill leads to torsions between the saddle and the handlebars, all the more with luggage, and what starts then is paddling", he explains. Often an accident resulted from the overreaction of the rider trying to bring his pedelec under control again.
However, to achieve optimum riding characteristics for pedelecs, the test engineer is of the opinion that the manufacturers should make the design with the riding stability in mind. The rucksack solution trekking bike plus motor were doomed to failure. Pedelecs were heavier and had several masses capable of oscillating in exposed areas which required increased attention during construction.
Although general physical conditions, such as tyre pressure and road conditions, were of decisive importance for the riding behaviour which can, however, not be involved as firm parameters into the development and fabrication, there are according to Zedler several criteria that manufacturers have to observe stringently when designing a pedelec: These are different stiffnesses, the weight distribution of various components and a number of geometric conditions.
The test institute determines values for these factors in benchmark tests and displays them in an octagon. The graphics shows how stable the pedelec rides and in which areas it can still be improved. "Due to the type-related restrictions, the optimum cannot be achieved for all models. Experience has shown, however, that minor improvements in all areas would help improving the riding behaviour of the pedelec," states Zedler in his conclusion.
Another subject relevant for the safety of pedelecs is treated by Zedler in the newsletter: the replacement of parts. This is a subject which lacks clear regulations. "As long as there are no highest courts decisions made, the statements of lawyers and other specialists remain expressions of opinions and must therefore be handled with caution. My advice regarding modifications on pedelecs is caution and proper proceeding from the side of the manufacturer as well as dealer."