Efficient, healthy, green - the humble bicycle (Happy 30th Brithday Sustrans)

What would stretch twice around the world if they were lined up head to tail? Answer: all the cars in Britain, according to The Ecologist magazine. To make things worse car traffic is due to increase by over a fifth in the next ten years, not least in Bristol unless we change our habits. So, its worth reminding ourselves of just how efficient, healthy and green that great piece of technology - the bicycle - is, especially since Sustrans the country's leading, and Bristol-based, sustainable transport charity is about to celebrate its 30th anniversary.

Primary energy use in cycling amounts to just 0.03 megajoules per kilometre! Even walking, which consumes 0.14 megajoules, is not this efficient. The average for a car with average occupancy is 2.1 megajoules per passenger kilometre whilst domestic air travel is also 2.1 due to its higher occupancy rates. Public transport fares better with figures of 1.1 per passenger kilometre for the average rail (about the same as a double decker bus) and 1.4 for a single decker bus, depending on occupancy rates. The most efficient forms of public transport, such as London Underground trains or certain forms of tram might achieve figures as low as 0.2 megajoules when fully occupied - still no match for the bicycle.

This makes the bicycle 70 times more energy efficient than the average car and 6 or 7 times more efficient than even the best forms of public transport running under the most efficient conditions. So, in terms of efficiency, my answer to the question 'Have you got any suggestions for improving transport in and around Bristol?' is to invest much more in cycling and try harder to create a cycling culture. More is also needed for public transport.

We need a cycling culture for our health too. One BUPA study found that childhood obesity had doubled in a decade. Over a third of children aged 2-7 years dont get enough exercise and nearly two thirds of teenage girls are classed as inactive. Contrast these figures with the fact that a 10% increase in the number of people riding a bike regularly would lead to a 4% reduction in people with heart disease, saving hundreds of millions a year in healthcare. And it would create a more pleasant, greener environment.