The small world of trials has witnessed over the years some engineers whose ideas and dreams had them thinking out loud and well outside the box, not conforming with the normal lines of what a trials motorcycle should look like. In my early teen years I rode the very forward-thinking Ossa powered MAC – Macdonald Auto Cycle – built and ridden by its builder Duncan Macdonald. It was years ahead of its time and very much the forerunner of many production machines we would see over the years; the early Beta Zero springs to mind. Duncan came from the family that gave us Vacuum Formers (VF plastic mudguards to the older readers) produced along with his late father John and Brother Andrew. The aircraft industry has always featured in motorcycle development, for example with disc brakes, and it was from this area, landing gear on the Concorde project, that French engineer Jean-Pierre Fournales used his ideas and experience to build the Fournales trials machine.
The project came to life over the winter months of 1981/1982 as Jean-Pierre had developed his own air shock absorber and decided to incorporate this and his other ideas around a revolutionary trials motorcycle manufactured as a test bed for his many thoughts.
The starting point would be the engine and he chose the Italian Hiro unit developed by Sammy Miller. This was maybe not the best choice; he would have preferred to use a Rotax engine but he was able to purchase complete Hiro engines in single units at a time. The situation of the gearbox sprocket fulcrum point was easily accessible for him to locate the swinging-arm pivot to remove all issues of drive chain and suspension interference when applying power. The machine was built in a small laboratory, where he had access to many test facilities he could use to equate the fracture points and understand the stresses induced in the frame’s fabrication.
Mixing novel, unique ideas whilst incorporating original ones the main frame structure was a cross between a backbone with bracing and anchor points included, giving a very ‘space-like’ appearance. The steering head assembly was not as we know it, with a conventional steering head spindle. It featured a clamp assembly machined by Jean-Pierre from solid billet aluminium, with bottom struts located on the other frame members to make the head angle easily adjustable.
A heavily braced, tubular, single-sided swinging arm was located directly to the gearbox output shaft. The rear air shock absorber was connected directly to the swinging arm to provide a more positive source of feedback. Ridden by Pierre Cauquil the machine attracted much interest wherever it appeared. He competed on it in the French championship events as well as a few world rounds.
Development focused around the rear suspension and its biggest claim to fame was when Pierre cleared the massive step at Bilstein in the 1983 World Championship round. Rear shock absorber development continued, and the Fournales Company can now boast over 37 years of manufacturing shock absorbers in fields as varied as transport, industry, recreational sports, competition and aeronautics. The company’s know-how is to design and produce innovative and efficient products with optimum manufacturing quality in the modern world.
The picture is of Pierre Cauquil in the 1982 Spanish World Championship round.