Nov 7th 2012, 17:47 by The Economist online
THE first bicycles were made of wood. After that, manufacturers used steel tubes. These days, for high-end bikes where weight is at a premium, they turn to aluminium alloys or even to carbon fibre. But Izhar Gafni, an amateur cyclist who owns a number of such high-end bikes, wonders whether the original inventors had a point. He proposes to go back to using wood-or, rather, a derivative of wood, namely cardboard.
Mr Gafni, who is based in Ahituv, Israel, spent years trying to work out how to make a cardboard bicycle able to support the weight of a human being. The trick is twofold. First, he folds the cardboard-commercial-grade material, made from recycled paper-to increase its strength. (He worked out the exact pattern of folding for each of the machine's components using the principles of origami.) Then, once it is folded, he treats the result with a proprietary resin that holds it in shape and stiffens it, before cutting it into the form of the component required. A second application of resin renders the component waterproof, and a lick of lacquer makes it look good. The result, Mr Gafni claims, is stronger than carbon fibre.
The bike's frame, wheels, handlebars and saddle are all made of cardboard in this way, and then fitted together. The tyres-again harking back to the early days of cycling-are composed of solid rubber, recycled from old car tyres. That makes the ride a little harder than if they were pneumatic, but means they cannot be punctured.
The chain, whose design is based on the timing belt of a car, is also made from car-tyre rubber. The pedals are plastic recycled from bottles. And the brakes are also recycled materials, though Mr Gafni is not yet ready to disclose exactly what. The finished product weighs 9kg and can carry a rider weighing 220kg.
Mr Gafni's target market is the poorer countries of the world. Since manufacturing the cardboard bike will, he reckons, cost $9-12 a unit, his velocipedes should find demand which metal bikes cannot. But people in rich countries may be interested too. In Tel Aviv, the commercial capital of Mr Gafni's native land, 2,000 stolen bikes were recently put on display by police, for their owners to claim. If bicycles cost less than the locks that chained them to lampposts, it might cease to be worthwhile stealing them.