Durability testing of the KS 601 at the Nürburgring, 1950. Wearing a cap is Ernst Schmidt, design engineer for the KS 601. In the center, in motorcycle leathers: Georg Weiss, competition rider and later competition chief at Zündapp.

There can be no doubt that the successes of the KS 601 in motor sports were an important factor in the model's popularity. Reliability trials that were extremely popular at the time, t he entire point was to push the limits of performance and endurance for both rider and machine – top speeds were not of interest.