By Michael Bristow
BBC News, Beijing

Office worker David Dai is one of a growing army of Beijing residents returning to two-wheeled transport.

But the 28-year-old does not rely on his own pedal power – like hundreds of thousands of others, he has bought an electric bike.

These battery-powered, and virtually silent, machines have become increasingly common on the streets of the Chinese capital.

With roads often clogged with cars – there are now four million vehicles in Beijing – they offer a speedy way to get around.

But not everyone seems to like them: government officials are unsure about how to deal with this explosion of electric bicycles.

Congested streets

China used to be known as the “kingdom of bicycles”. In the 1980s, four out of five commuters pedalled to work on them in Beijing.

But as the capital’s residents became richer following economic development, they ditched their bikes for four-wheeled transport.

Recent statistics suggest that only one in five city residents now use an ordinary bicycle to travel around.

In a matter of just a few years Beijing has gone from a city with few private cars to one where traffic jams are commonplace.

But many Beijing residents are now buying electric bicycles to avoid wasting time on congested streets.

“It takes only 10 minutes to ride my electric bike from home to work,” said Mr Dai.

“If I took the bus, I’d have to spend time waiting for it, and then I could be trapped in a traffic jam. It could take me half an hour to make the same journey.”

These bikes are on sale everywhere, with shops sometimes clustered together. Their wares are lined up on the pavement in neat rows.

Zhang Zhiyong, the manager of a store selling a brand of electric bike called “Capital Wind”, said it is easy to see why sales are booming.

“Beijing is not like other smaller cities – it’s big. If people ride their bicycles to work, they get really tired. If they drive to work, the roads are often congested,” he told the BBC.

“But an electric bike is environmentally friendly and convenient. Promoting the use of these bikes would benefit us all.”

And they are much cheaper than cars. The most expensive model in Mr Zhang’s shops is only 2,680 yuan ($390: