Klaus Müller began his career as a 19-year-old working as the team manager of an international motor racing (Warsteiner racing with Rolf Stommelen). Next step was a similar task in the German ATS-Formula 1-outfit.

As a freelancer he looked after management, Public Relations and sponsors for Formula 1-drivers Christian Danner and Marc Surer. At the same time he cooperated with Cosmos GmbH, a subsidiary of Sport-Informations-Dienst (sid), promoting great events including the opening of the new Nürburgring.

After he managed to win the Italian Jeans-company Rifle as a sponsor, he followed the invitation to run their German subsidiary as Director Sales and Marketing. After four successful years he moved to Falke Fashion, being responsible for Sales and Marketing, including the BOSS-licence-collection.

In winter 1989 he founded DOS-Y-DOS Fashion GmbH which designed, produced and distributed his own brands (DOS-Y-DOS, Centigrade, B-Have), developed and introduced licence-collections such as Chesterfield and f6 (Phillip Morris), Project Seven (ProSieben-TV) and Kangol and produced textile merchandising for the BMW-Williams-Formula 1-team.

After selling his shares in 2000 he formed Tinarista Communications GmbH and managed various projects in the Sales, Marketing and Business Development-area.

In 2011 taking over the A:XUS brand for highend-carbon racebikes. In 2015 starting a retail concept with e-bike-engine builder Brose. Since 2017 running a premium-retail-concept for cycles under the own brand THE FLEMISH CAP.