3 TYPES OF FUNNY FRONT END
Hub Centre Steering
Basically a HCS has a wheel axle through the centre of a very large diameter hub, inside of which is a king pin about which the steering occurs. There are two hubs, one stationary and one rotating. The stationary hub is prevented from rotating, usually, by means of an upright structure which itself is located by a link back to the main chassis. Another link back to chassis from the axle completes the linkage. Today the most known example is the Vyrus derivative of the Bimota Tesi.
4-bar linkage or double-link
BMW’S Duolever system, the Yamaha GTS1000 from the 90s, Hossack and the Cortanze ELF endurance racers from the 80s are wellknown examples of this.
The Hossack and its many derivatives (eg BMW Duolever) have both links above the wheel. The ELF type have both links within the circumference of the wheel, which requires the use of bent links for steering clearance. My own designs and the Yamaha GTS have one link above the wheel with the other within the wheel and bent.
The Hossack is the only one which allows for the use of standard wheels and brakes – which lowers cost and simplifies construction. The other two options require special single-sided wheels (ELF’S work led to the singlesided swingarm).
These are funny front ends with sliding elements like telescopic forks, but with some form of pivoting link to provide extra stiffness and modification to the geometry of movement. In many ways this is a design based on a desire for improvement in performance whilst retaining the familiar look of telescopic forks. BMW’S Telelever is an example, 20 years after British special-builder Saxon produced limited road bikes.
The ELF racer and its anti-dive characteristics meant that funny front ends were associated with highperformance applications. But telescopic forks have improved way beyond what was thought possible prior to the 1990s and racers use braking dive to their advantage.
FFES also tend to be kinder on tyres and generate less heat which reduces grip and rider feel.
Good designs have a lot to offer the road rider in terms of stability and confidence but forget about them in topclass racing at least for the near future.
There is a lot of information on various funny front ends in my chassis book, details on www.tonyfoale.com
BMW used Duolever for some of their K-series machines
British firm Saxon came up with an early Telelever type
Hub centre steered ELF 500