Riding characteristics and batch quality – Accurate testing and benchmarking

Bicycles and e-bikes are on the move, often every day and on varying surfaces. Our PERFORMANCE testing systems measure their riding characteristics as well as the characteristics of individual components. They provide measurement values, such as head tube stiffness, i.e. riding stability and comfort, under comparable conditions.

As a result, you obtain from us reproducible figures of riding safety and performance including the "Stiffness-to-Weight" factor (STW), a term which was coined by us, plus precise benchmarking with products of competitors and the test results of various bicycle magazines.

In addition, we check for you with our PERFORMANCE systems, whether a production batch is of continuously high quality.

Our further SAFETY testing services in the accredited test laboratory ensure reliable tests in accordance with important standards for electric bicycles/e-bikes, bicycles and transportation/cargo bikes, such as the DIN EN ISO 4210, the DIN EN ISO 8098, the DIN EN ISO 11243, the DIN EN 15194 and the DIN 79010 standards. Where necessary and reasonable, the standards are supplemented by company-own test criteria.

These are based on our longstanding accident analyses and were verified and validated with scientific support by universities. You find a detailed list comprising the current scope of accreditation in the (German) annex tot he certificate and in the (German) internal annex to the flexible scope of application.

Siegel - das den erreichten Sicherheitslevel ausweist

FAQ – the most important key words

For us, it is important to work in a transparent and comprehensible manner, because understanding means confidence.

To create the basis for this confidence, we have collected the most frequently requested key words in an overview. In case your inquiries remain unanswered, drill us with questions!


"Standardised weight" means the weight of the frame ready for assembly. That means rear derailleur hanger, seat clamp, front derailleur mount or clamp and cable guide under the bottom bracket are included.


At Zedler – Institut für Fahrradtechnik und -Sicherheit GmbH the measurements and tests are performed exclusively on state-of-the-art precision machines undergoing regular checks and maintenance. Because only with weight determination to the gram, the indication of STW makes sense at all.


Every stiffness value is based on several measurements, i.e. the unit under test is mounted several times on the testing system with two measurements at least being taken respectively.

This is to eliminate various influences, such as distortions etc. To assess the resistance against elastic deformation 6 individual measurements to obtain the respective value are carried out at least.


Stiffness-to-Weight (STW) is a calculated key figure indicating the ratio of stiffness per kilogram material. This key figure of material utilisation is an indicator for the structural performance and mainly of interest with high-end sports equipment where a careful treatment by users can be assumed.

To ensure a benchmarking of the measured frame with regard to STW, the weight is standardised and exclusively related to frames ready for assembly.


The measurements are carried out in accordance with the indicated standards on machines identical in construction. Deviations from values that are published in the specialist magazines of Delius-Klasing Verlag are either within the measurement inaccuracies (+/- 2 %) or, in the case of major deviations, to be attributed to deviating frame sizes or modified designs.

The results are, however, not comparable to values determined by means of other test stands that are not absolutely identical in construction! The numerical result is influenced to a considerable extent by the way the unit under test is mounted and by the actual measuring point!