PIONEER TECH­NOL­OGY

Classic Bike (UK) - - 19th Century Trikes -

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

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