Zedler – Institut für Fahrradtechnik und -Sicherheit GmbH, headquartered in Ludwigsburg, is part of the Zedler-Group and has specialized in the development and construction of testing systems for bicycles and e-bikes since 1994. In its in-house test laboratory, bicycles and components such as frames, handlebars, saddles, and luggage carriers are examined for fatigue strength – both on behalf of manufacturers and retailers for prototype validation, and for insurers and courts in the context of expert reports related to accidents or damage cases.
In addition to conducting tests, the company develops and manufactures its own testing machines, which are deployed globally in the test laboratories of leading bicycle manufacturers. The Zedler-Institut also produces standards-compliant user manuals and documentation for bicycles and e-bikes. With four dynamic laboratories, around 50 fatigue testing systems, and a consistently sustainability-focused corporate strategy, Zedler-Institut is now recognized worldwide as a trusted partner for quality and safety in bicycle engineering. “We are a classic hidden champion with customers all over the world, even though we are primarily known within the bicycle industry,” explains Dirk Zedler, founder, testing expert, and certified bicycle expert.
Not all bicycles are the same – requirements for testing systems
Bicycles and pedelecs are in constant motion, often used daily and across varying terrain. Bicycle frames range from compact folding bikes with 16-inch wheels to cargo bikes with wheelbases of up to 2.15 meters and differently sized front and rear wheels, as well as tandems for two riders. In addition:
- City bikes often feature a low bottom bracket, allowing riders to comfortably place their feet on the ground when stopping at traffic lights.
- Mountain bikes (e.g., enduro models), by contrast, require significant ground clearance to prevent the pedals from striking obstacles off-road, even under suspension compression.
To accurately replicate different geometries, wheelbases, and bottom bracket heights, testing systems must therefore be highly adjustable while also maintaining exceptional stiffness and long-term durability, as they are required to apply precise loads to a wide range of bicycle frames over many years.
Tailor-made testing technology at the highest level
To ensure that a frame can withstand long-term cyclic loads, bicycle engineering relies on a standard test known as “bottom bracket fatigue” (BBF). The bottom bracket is one of the most highly stressed areas of a bicycle – it is where the pedals are connected to the frame via the crankset. Each pedal stroke generates alternating torque, bending, and torsional forces that accumulate over time. Without sufficient structural integrity, cracks may develop, ultimately leading to failure.
In its laboratory, Zedler-Institut simulates the forces generated by a rider pedaling – so-called “pedaling forces.” The bicycle frame, including the installed bottom bracket, is subjected to repeated artificial loading. This makes it possible to determine how many load cycles the frame can withstand before initial signs of damage such as microcracks, creaking, or bearing play occur. The BBF system developed by Zedler-Institut is characterized by its high adaptability to different bicycle types and its robust, durable design. Once all parameters are set, the testing system reproduces the cumulative pedaling loads experienced over a bicycle’s lifetime within approximately 24 hours.
The Zedler-Institut works exclusively with in-house developed testing systems, such as the “Performance” testing machines. These systems measure both overall riding characteristics and the properties of individual components, delivering reliable data on ride stability, safety, and comfort under comparable conditions. They also enable conclusions about the consistent quality of production batches.
Powerful test systems, reliable components
When building its testing machines, Zedler does not rely solely on in-house expertise but also on partners such as Norelem, whose extensive portfolio of standard and operating components for mechanical and plant engineering provides a wealth of ideas and solutions that continuously inspire Zedler’s development work.
Norelem is an internationally active company based in Markgröningen near Stuttgart and has been supplying high-quality standard components and system solutions for over 60 years. Its product range now includes more than 130,000 standard and operating components, such as aluminum profiles, joints, control elements, clamping technology, as well as measuring and testing equipment. Free CAD data, a user-friendly online shop, and high component availability complete the offering.
For the design of its testing machines, Zedler-Institut regularly uses Norelem components, as founder Dirk Zedler explains: “We started very small and initially ordered clamping levers from Norelem – a classic standard component. Today, we use an increasing number of parts, including complete systems such as linear guides with corresponding braking elements.” The custom-built testing machines are thus created through an “intelligent interplay of Norelem profile guide rails, guide carriages, clamping elements for profile guide rails, custom-manufactured special components, profiles and accessories from a common aluminum profile supplier, and smaller Norelem parts such as clamping levers, various rod ends, fitted bolts, and more.” Zedler has found that using Norelem standard components significantly extends the service life of its testing machines and improves precision – resulting in increasingly accurate and reliable test results.
No signs of fatigue: continuous improvement in practice
Anyone entering the Zedler-Institut inevitably encounters the so-called “Walk of Fail”: a 30-meter display of broken bicycle components – parts that did not fail on testing machines, but in real-world use on roads or off-road terrain. “And that is exactly what we learn from,” explains Dirk Zedler, “to make our testing machines and procedures even more robust and continuously improve them.” For 15 years, the company has relied on its partnership with Norelem: “We have worked with Norelem for so long because their broad product range continually provides new approaches for optimizing our systems.”
This collaboration extends far beyond the supply of components. Zedler particularly values “the reliability, delivery performance, and overall service. In our work as bicycle experts for the bicycle industry, we have had some negative experiences with parts sourced from online marketplaces. That is why we deliberately avoid such sources and rely on the safety and quality provided by Norelem.”
The enthusiasm is mutual. “Working with the Zedler team is something special for us,” emphasizes Dirk Langenohl, Key Account Manager at Norelem. “It is inspiring to see how our standard components are used in highly complex testing machines – and how this ultimately contributes to greater safety for cyclists worldwide.”
Both companies are committed to continuing their collaboration. Zedler continues to grow, constantly develops new testing systems, and supports an increasing number of manufacturers. “Every time we build a new system, we discover something new within the portfolio – and that, in turn, inspires us in other areas. This is how our partnership with Norelem continues to deepen,” says Dirk Zedler, looking ahead.
About Norelem
Norelem supports design engineers and technicians in mechanical and plant engineering with standardized components for implementing design solutions. Its clearly structured online shop offers more than 130,000 standard and operating components available immediately, including free CAD data for faster design processes without the need for drawings or configuration. With the “Norelem ACADEMY,” the company is also actively involved in promoting young talent, offering technical training, seminars, and product training programs.
