"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!
