In 1986 the active triathlete Zedler worked in a bicycle shop and intensified his interest in the bicycle. In 1988 he wrote his theses about carbon. On April 1, 1993 he set up his own business. In 1994 he built the first stiffness test stand. Today, his business has 15 employees; since 2010 he has the right to name his company "institute".
Zedler offers a wide portfolio of technical services like scarcely any other company. It includes the development of user manuals, the preparation of experts’ reports as well as extensive product testing. Some of the test stands will be presented by us in words and pictures. User manuals can be ordered in numerous languages (supplying a user manual in the language of the target market is required by law). The user manuals are kept up to date also in terms of the legal frameworks. Zedler is also eager to note that the user manuals from his house are always among the good ones in the bicycle tests carried out by the German product testers (Stiftung Warentest). Zedler’s opinion about the significance of the Stiwa tests is a different matter.
More than 700 experts’ reports to date provide a serviceable overview over damage frequencies, which interlocks good with the testing. Test requirements can be set up quite realistically. At Zedler’s institute the customer can have tested his products on different levels, i.e. from Basic over Advanced to Advanced Plus tests.
Lectures: From carbon to damage frequency
The owner of the institute delivered a number of lectures on damage of carbon products and pedelecs as well as operational safety determined by technical tests.
Zedler has a special interest in carbon, as it is a composite material made of fibres and a matrix. Which means that carbon alone is not yet a material. Your must, however, know the special features of the material, for example that carbon does not show a deformation before it breaks. If the frame shows cracks, it may be that they only affect the paint as it could not follow the movement of the carbon. Carbon is stable in tensile direction, in compression direction it is not.
According to his experience, the bicycle claims in practice mainly concern road racing bikes. The reason: "Road racing bikes are used longer than mountain bikes." Freeriders and dirt bikes on the other hand are more frequently concerned by theft and burglary. Dealers should not import carbon products from China on their own, as in this case they will not know what they will get. As meanwhile any component is made of carbon, you have to be careful in particular with the clamping issue. Canyon supplies a torque wrench with every carbon seat post, as feeling is an insufficient indicator. Once, Zedler gave Allen keys to a number of people and asked them to tighten. They applied torque values between 2 and 40 Newton. For safety reasons seat posts should have two bolts.
Broken handlebars play an important role when it comes to pedelec damage in practice. Handlebars bearing the load on standard bicycles, break more often on pedelecs. The spokes are also parts concerned by damage, i.e. when the motor is located in the wheel. In this case the spoke has to bear another kind of bending, when the punches in the rim holes are not directed respectively. Gear hubs do not always go well with mid-mounted motors; they do not like the increased torque. Pedelecs’ centres of gravity are often lower; therefore more efficient braking forces may act without bringing the bicycle close to overturning. Front wheel motors pull at the fork. On bad trails the motor may swing upwards and damage the fork. Bottle cage eyes are not designed to hold batteries.
Low-step-through models have monotube frames and therefore no redundancy. In this case a broken frame may be very serious, whereas a broken diamond frame often even allows a careful riding home. Chains may tear, if you do not relieve the drive train during shifting. This may result in a risk of accident, if the motor still moves although pedalling has stopped.
All in all no conspicuous patterns in the number of material defects on pedelecs have shown to date. The riding characteristics, however, change. Taking account of the high unsprung mass Zedler advised against speed pedelecs without suspension forks; otherwise there is the risk that the vehicle can hardly be held under control. Front-wheel motors should only apply moderate torques; otherwise the bicycle could get out of control. Another problem of major importance in Zedler’s opinion is the fact of being underestimated by other traffic participants.
Good product – Good manual
The German Supreme Court has confirmed that the DIN EN standard is not binding.
In France, however, it has force of law. EU compliant user manuals are required in any case.
In view of the market surveillance by the trade licensing offices Zedler states: With a very good user manual available from the beginning, there is no distrust against the product by the controllers and the product will not be taken to pieces by them. In general, there is in Zedler’s opinion the need for the EN standard to be reworked; in the trekking bike standard for example there is nothing stated with regard to fatigue in the head tube area. A future standard for pedelecs should reflect the modified loads and uses to allow a realistic testing. All in all, the Zedler institute is among the key partners of the bicycle and bicycle component industry when it comes to the technical optimization of the products. Especially for new materials and material combinations as well as for new bicycle types they may deliver essential knowledge, to design bicycles and components suitable to realistic loads.
Author: Michael Bollschweiler