Thirty years ago, the bicycle was the king of China's city streets. Rivers of bike riders streamed almost unchallenged through every city and town, and a bicycle was one of the most coveted wedding presents a couple could receive. Today, a shiny new car is the status symbol of choice, and bike riders are being edged off the congested streets. The issue of bikes versus cars is drawing attention in China's biggest city.

Shanghai is a city of 20 million people and almost 10 million bicycles.

It is also a city of traffic jams. China's new love affair with the motor vehicle is forcing bike riders to contend with a tangled, smoky mess of taxis, trucks, buses and private cars.

With the 2010 World Expo on the horizon, the Shanghai government is under pressure to impose some sort of order on the streets - and it seems that the once-supreme bicycle is a main target.

Last December, Shanghai officials unveiled a plan that would prevent cyclists from riding on many of the city's major routes.

Angry letters to newspapers followed, and in January, many cyclists simply ignored the bike ban. In February, the government bowed to public displeasure, and announced the construction of a new network of bike paths to be built throughout the city.

But it is still tough for cyclists in Shanghai, as they fight for space with aggressive motorists, many of whom have only just obtained their licenses.

Shanghai's roaring economy is characterized by the rapid construction of tall glass buildings and modern highways. But many Shanghainese still squeak by on an average salary of $200 a month...a small enough amount that people worry about the price of public transportation.

One woman says it costs three or four yuan every day to take a bus to work. She says bicycles are more convenient and more flexible: if a road is jammed, you can find new routes. And not everyone can afford a car.

The Shanghai government's attitude towards transportation is typical of that in many Chinese cities. While municipal governments elsewhere in the world are trying to encourage bicycle riding, Shanghai is trying to limit the number of bikes. Air quality - already far below what would be tolerated in the West - may suffer even further.

Lester Brown is president and senior researcher with the Worldwatch Institute, an environmental think tank based in Washington, D.C. He says China's environment will not be able to sustain a car-based transportation system for long.

"What if China succeeds in developing - in using the Western industrial development model? That is, [a] fossil fuel-based, automobile-centered, throwaway economy," he said. "And if someday China has a car in every garage, and maybe two cars in some garages, American-style, China would need more oil than the world currently produces, and may ever produce, so that's obviously not a viable option."

The motor vehicle's role in environmental damage is already evident in Shanghai. According to a recent study by the government, 90 percent of the city's pervasive air pollution is caused by cars and trucks.

China's new emission standards will require cars to become 15-20 percent more fuel-efficient, but that gain is quickly swallowed up by the growing number of vehicles in urban centers. Officials estimate the number of private cars in Shanghai has risen 80 percent in the past two years - and there is no sign of a slowdown in sales.

Fred Moavenzadeh, Professor of Urban Transport at the Massachusetts Institute of Technology, says cities in developing nations go into a downward spiral when they begin to cater to the needs of car owners.

"China is basically trying to do the mistakes that everybody else has done: build more highways, which attracts more automobiles, build more automobiles that then allows people to travel and spend less obviously on mass transit," he said. "Therefore, they are creating automobile dependency, which, then, later on, they don't know how to cope with."

Despite the booming economy and the lure of a new car, many here say that they have been cycling for so long they cannot imagine storing away their bikes forever.

For many, cycling is a way of life that isn't quite ready to disappear.