Annual report 2017

Safety improvement for pedelecs

System analysis, operational measurement, operating loads, pedelecs, customer usage, usage simulation

One in seven bicycles currently sold is a pedelec. But do their test standard actually meet the harsh demands of everyday use? To get to the bottom of the matter, the Zweirad Einkaufsgenossenschaft (ZEG) [Bicycle Purchasing Cooperative] launched the research and development project “Quality Initiative E-Bikes”. Fraunhofer LBF is the scientific partner. The aim is a dependable quality and safety standard for pedelecs.

Demanding use in real-life tests

After in-depth analyses of the currently applicable standards for strength and driving safety, Fraunhofer LBF discovered that they are not always scientifically robust. Mileage or permissible total weight, for example, are not taken into account apart from during the brake test. Dynamic driving effects such as handlebar flutter are also ignored. For manufacturers, the currently applicable standards and guidelines do not provide any adequate specifications for state-of-the-art mechanical testing of pedelecs. The standards can serve as a guide for manufacturers but checks must be carried out to ascertain whether the tests described in them adequately cover demanding use by the customer.

To determine how high the loads on pedelecs are in actual use, the project team together with the ZEG defined user types and their riding habits. This information was used to define a complex program of test drives, experiments on test rigs and simulations. The focus here was on the test drives during which the operating loads occurring were recorded by means of measuring technology installed on the pedelec. During these realistic everyday cycle trips, parameters such as rider’s weight, payload, speed, route profile and also riding over curbsides and steps were recorded and varied so that they corresponded to the usage, vehicle and user characteristics known from the field investigations. Proposals for adapting the tests of the existing pedelec standards were made based on the studies carried out.