A sketch proposal for the BMW K100RS motorcycle (1979). Originally this was a modular concept with interchangeable components for the base, RT and RS models. The final design, which was basically unchanged and in production for a decade, retained much of this design sketch including the patented (Kasten/Fellstrom) screen aerofoil.

Below the full-sized model being tested at Pininfarina's windtunnel in Turin, Italy. Tests over many days included sitting ourselves on the model, in place of the test dummy, to get a realistic feel for how effective the aerofoil was and what impact it might have on the rider and bike.