In a three part audio news story, BBC's Mark Stephen discovers the importance of the bicycle as a global barometer of social, economic and environmental change:

• Part 1 - 17 July 2006
  Namibia's scattered population faces a huge struggle against poverty and AIDS. A bicycle can provide great freedom - access to healthcare, education and work - that sheer distance often renders impossible. Taking a trip across this vast country, Mark sees for himself the impact that owning a bicycle can have on the lives of Africa's rural poor.
  
• Part 2 - 24 July 2006
  Over 200 years after its invention, it could be that the humble bike will once again be king of the road in the developed world. Alongside an increasing number of commuters, Mark Stephen braves the cycle lanes of London.
  He then travels to Denmark to discover whether a cycling revolution in the UK could ever match the number of cyclists who take to the streets of bicycle-friendly European cities like Copenhagen.
  
• Part 3 - 31 July 2006
  In China, the bicycle has long been the transport of choice, but economic growth has encouraged an explosive growth of cars. In 2006 alone, China is expecting to put a further 6 million cars on the road. Taking an intimate journey through Beijing, Mark meets individuals whose lives have been inextricably tied to the bicycle for generations, and discovers that the bicycle is now at the very heart of a new environmental threat.