Upgrading the suspension and brakes on your motorcycle can greatly improve its handling performance. But for those with the time and money, why not take it a step further? That’s exactly what HB-Custom in Germany did with their latest project—a Honda CB900F featuring a race-bred Rau frame.
The Rau frame, designed by German frame builder Manfred Rau, is a rare find and highly sought after. Holger Breuer, the owner of HB-Custom, managed to source a 1977 Rau frame and a Honda CB900F to build his custom masterpiece. With no budget restrictions, the goal was to create something truly special.
The stock CB900F engine was pulled out and rebuilt to 1,062 cc, featuring rebored cylinders and forged Mahle pistons. To meet Germany’s strict regulations, the bike is equipped with Mikuni RS36 carbs and a custom carbon fiber airbox. The engine now produces close to 100 horsepower and is complemented by a digital ignition and hydraulic clutch for modern reliability.
The Rau frame was perfectly designed for the CB900F motor, making the installation a straightforward process. Holger completed the rolling chassis with front forks and yokes from a Suzuki GSX-R1000 K7 and a Wilbers shock at the back. To enhance stability, a Wilbers steering damper was also added. The bike rolls on custom-built 17″ wheels from PVM, wrapped in Pirelli Diablo Supercorsa tires and equipped with Yamaha R1 and R6 braking components.
With only the engine to work with from the original CB900F, Holger had to create the rest of the bike from scratch. He shaped aluminum sheets to form a new fairing, fuel tank, and tail section. The design borrows elements from café racers and vintage race bikes, with sharp edges that pay homage to the CB’s heritage. A cutout on the right side of the fuel tank showcases the distinctive backbone of the Rau frame, and a handmade “fuel gauge” adds a unique touch.
Other notable features include an MRA windshield, LED headlight from Koso, taillight from Highsider, and turn signals from Kellermann. The cockpit houses a Motogadget speedometer and RFID ignition receiver, with Gilles Tooling clip-ons, Magura levers, and Highsider switches. The bike also boasts carbon fiber and drilled parts, Gilles Tooling rear-set foot pegs, a custom license plate bracket, and a four-into-one exhaust from Schüle.
The Rau Honda CB900F by HB-Custom is finished in a dark teal color with subtle black graphics, giving it a subdued yet elegant appearance. Its true wildness, however, lies beneath the surface. While we can only imagine the glorious sound it produces at full throttle, we can’t deny its captivating aesthetic. It’s a testament to the passion and craftsmanship of Holger Breuer and his team at HB-Custom.