Stephen Brett caresses the brass fuel tank of his De Dion-engined Phebus and beams with pride. And no wonder – in 1899 Charles Jarrott hit 39mph on one these at the Crystal Palace Velodrome. Based in Suresnes, just outside Paris, Phebus learnt a lot from their racing exploits. “In 1900 they made a longer, lower and wider chassis with a slightly sloping top frame tube,” he explains. “Lowering the centre of gravity makes a trike much more stable in the turns.”
Although the Phebus features a differential in the back axle and a Bozier two-speed gearbox with clutch, it still has a surface carburettor. The triangular tin box under the saddle acts as both a primary petrol tank and carburettor. Poking through the top is a telescopic tube or chimney that acts as the air inlet, with a flat ‘baffle plate’ soldered to the bottom. Passing through the chimney is the stem of a float that indicates the petrol level. The rider lifts or lowers the air inlet tube so that the stem projects 10-15mm above the petrol.
Pioneer riders used much lighter petrol than is available at the pumps today – it was more like watch cleaning fluid. To make the petrol even more volatile, a tube from the exhaust pipe passes through the tin box to warm it up. On the suction stroke of the engine, air is sucked down the chimney and under the ‘baffle plate’, picking up the vapour from the surface of the petrol. This rich mixture is sucked up to a double-barrel valve, with two control levers connected by long rods to the frame top tube. One valve lets in extra air, while the other valve leads to the inlet pipe. The rider needs to skilfully manipulate the levers, because every time he goes over rough ground the petrol slops around inside the tin and makes the mixture richer.
“I’m constantly playing with the ignition and throttle controls and trying to get the best from the engine,” says Stephen. “Every five miles I have to reach behind and use the plunger pump to squirt oil in. You might say that’s why riding a De Dion Trike is so exhilarating!”
Stephen Brett with his surface carburettor-fed Phebus built in 1900