Revealed: The greenest bike ever made

For the first time eco-conscious (but wealthy) Londoners can buy an organic, biodegradable bike - made from bamboo.

The frame of the Calfee, which will set you back at least £3,000, is made from stems hand-picked in the remote mountains of Taiwan's Yushan national park, home to wildlife such as the Formosan black bear and rock monkey.

The bamboo is shipped - not flown - to California, where stems are smoked and heat-treated to prevent splitting, and assembled into a frame, the pieces connected with lugs made of hemp fibre.

They are then coated in a satin polyurethane sealant.

The finished product is transported to Chiswick, where it is being sold in the Eco Age shop owned by actor Colin Firth, his Italian wife Livia Giuggioli, and her brother Nicola.

Five have been sold in Britain so far, including two in London.

The bike - available in racing or mountain format - weighs roughly the same as its metal equivalent but has none of the environmental baggage that comes with the manufacturing process.

About 60 per cent of the finished product is made of sustainable materials.

Bamboo is stronger than mild steel and more elastic than carbon fibre - meaning it absorbs shock exceptionally well.

Rachel Hammond, founder of British distributor RAW Bamboo Bikes, said: "Because bamboo is a natural material it takes a lot of the vibration out of the ride."

The Evening Standard gave the Calfee a road-test. It is a thing of natural beauty, pared-down and sleek - although the lack of mudguards is not an advantage when biking in London.

Lightweight, durable and highly manoeuvrable, it turned on a pin. The ethical benefits are obvious. Bamboo is sustainable - the fastest growing woody plant.

The co-operatives that chop and sort it in Taiwan are involved in a social project helping local people who come from disadvantaged backgrounds.

Company founder Craig Calfee is also involved in a project in Africa to help local entrepreneurs make bamboo bikes. But a vehicle of such political correctness comes at a price.

The basic frame costs £2,175 and customers must buy the other pieces as add-ons - meaning the finished machine costs from £3,000 to £3,500, depending on the specification.

The beauty of bamboo

Bamboo absorbs about five times as much greenhouse gas as a "conventional" tree plantation.

It does not fatigue like metal. But it does have to be coated with a waterproof sealant.

It supports a greater load than mild steel can without breaking.

In the Far East it is often used as scaffolding during skyscraper construction.

It is the fastest growing plant: some species can grow 1.5 metres a day. The bamboo used for the bikes takes four to five years to grow.

Each bike needs 2.7 metres of bamboo to make.

Each bike frame weighs only 4-5lb, but the finished product weighs 18-19lb.