- Patent for electrohydraulic power steering in combination with wheel hub steering
- Based on the Cyclone RA1000 with 996 cm³ V2
- Front wheel with single-sided swing arm, hydraulic steering transmission, and special brake system
The Chinese Zongshen Group is working on an unusual chassis concept that combines two technologies that have been rare in motorcycle construction to date. For the first time, wheel hub steering is to be combined with servo-assisted, hydraulically controlled steering instead of a telescopic fork. The patent applications that have now become public show how this system could be integrated into a production motorcycle.
Technical basis: Cyclone RA1000 and familiar components
The starting point for development is the Cyclone RA1000, which is now on the market almost five years after its first appearance as a concept vehicle. The naked bike uses a 996 cm³ DOHC V2 engine based on an earlier Aprilia design. It delivers 105 hp, equivalent to 77 kW, and maximum torque of 95 Nm, which corresponds to around 70 lb ft.
The engine is based on the Aprilia Shiver and Dorsoduro power unit. The frame is also based on the familiar Shiver architecture, which continues to be produced in China as part of a joint venture between Piaggio and Zongshen. While the reissued Shiver is visually very similar to the 2007 original, the Cyclone RA1000 has a much more massive appearance. A single-sided rear swing arm and a very wide rear tire characterize its appearance.
Wheel hub steering with single-sided swing arm at the front
The patent specifications show how the existing chassis of the RA1000 could be converted for an alternative front suspension. Instead of a telescopic fork, a single-sided aluminum front swing arm is used, also designed as a single-sided swing arm. The front wheel is unusually wide and is specially designed for wheel hub steering.
One advantage of this principle is the separation of steering, suspension, and braking forces. Braking forces are transmitted directly to the frame, while the suspension remains largely unaffected. In addition, the breakaway torques typical of telescopic forks, which can be caused by static friction, are eliminated.
Electrohydraulic power steering without mechanical connection
Particularly striking is the absence of a classic mechanical connection between the handlebars and the front wheel. Instead of linkages, deflection levers, or tie rods, Zongshen relies on a purely hydraulic transmission. Two piston rods are located below the handlebars, which detect steering movements and transmit them to an electrohydraulic system.
The central element is an electrically driven hydraulic pump. Two lines lead from it to a slave cylinder on the front wheel hub, which performs the actual steering movement. At the same time, the system is designed to provide feedback to the handlebars, thus enabling a defined steering feel.
The power assistance is intended to prevent the wide front tires from requiring excessive steering force. At the same time, the electronic control system opens up additional possibilities for assistance systems.
Basis for driver assistance systems
In contrast to cars, where power steering primarily increases comfort, a different aspect is paramount in motorcycles. Electronically controlled steering can actively intervene in the driving process. The patents hint at possible functions such as speed-dependent stabilization, cooperation with ABS and traction control, and more advanced assistance systems.
Stabilizing steering impulses, lane departure warning systems, or warning systems for imminent frontal collisions are conceivable. Comparable research projects are also underway at BMW, Honda, and Yamaha, but have not yet been implemented in series production.
Special brake system for the front wheel
The single-sided front swing arm also requires a modified brake design. Instead of two external brake discs, a single internal disc is used. This is operated by two opposing, radially mounted two-piston fixed calipers. The system is, of course, designed for use with ABS.
The compact design allows the brake system to be neatly integrated into the wheel hub despite the wide front wheel.
Opportunities and known disadvantages of the design
Wheel hub steering systems have been considered technically interesting for decades, but have never caught on. The disconnected steering feel, higher weight, complex mechanics, and higher costs are among the known criticisms. Zongshen’s concept does little to change these fundamental disadvantages. The additional power steering further increases the technical complexity.
At the same time, the Chinese motorcycle industry has shown a greater willingness to question established design principles in recent years. Zongshen is considered a manufacturer that can be trusted to actually bring such a system into series production.
Production readiness and outlook
The frame depicted in the patents largely corresponds to that of the Cyclone RA1000. Only in the front area are the necessary adjustments for the swing arm, hydraulics, and steering visible. Since the RA1000 is already equipped with a single-sided swing arm at the rear as standard, a version with single-sided suspension at the front would fit in well with the existing design concept.
Whether and when such a variant will actually come onto the market remains to be seen. However, the patent application shows that Zongshen is not only working on detailed improvements, but also on fundamental changes to motorcycle technology.
What does this mean for me as a motorcyclist?
If such a system were to go into production, the riding experience would be noticeably different from that of a conventional motorcycle. Servo-assisted wheel hub steering could reduce the steering forces required, especially at low speeds and when maneuvering, particularly on heavy motorcycles with wide tires, although this is actually negligible on motorcycles. At the same time, the structural separation of steering, suspension, and braking forces promises more stable handling during heavy braking, as the typical brake dive effect is largely eliminated. On the other hand, a different steering feel can be expected, which may be less direct than with a classic telescopic fork. In addition, there is more technology, higher weight, and potentially higher costs, both in terms of purchase and maintenance and repair. Whether the advantages outweigh the disadvantages in everyday use is likely to depend heavily on the tuning of the system and personal riding style.
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