Ivan Illich on the efficiency of bicycles

DSLC

Energy and Equity, by Ivan Illich, has some interesting comments on the efficiency of bicycles.

To quote:

Man on a bicycle can go three or four times faster than the pedestrian, but uses five times less energy in the process. He carries one gram of his weight over a kilometer of flat road at an expense of only 0.15 calories. The bicycle is the perfect transducer to match man's metabolic energy to the impedance of locomotion. Equipped with this tool, man outstrips the efficiency of not only all machines but all other animals as well.

and ....

Bicycles are not only thermodynamically efficient, they are also cheap. With his much lower salary, the Chinese acquires his durable bicycle in a fraction of the working hours an American devotes to the purchase of his obsolescent car. The cost of public utilities needed to facilitate bicycle traffic versus the price of an infrastructure tailored to high speeds is proportionately even less than the price differential of the vehicles used in the two systems. In the bicycle system, engineered roads are necessary only at certain points of dense traffic, and people who live far from the surfaced path are not thereby automatically isolated as they would be if they depended on cars or trains. The bicycle has extended man's radius without shunting him onto roads he cannot walk. Where he cannot ride his bike, he can usually push it.

I haven't verified his figures, but even allowing for a considerable margin of error the argument he presents for using bikes is still very strong.

Capt'n Midnight

I think the patent on using slats to channel a crosswind in the direction of cycle lanes has almost run out.

The main problem with cycling and any outdoor activity in this country is not the weather. It's the lack of shelter from it. Bus use and walking in general would probably increase if more bus shelters were covered and if you could find shelter on your way on short journeys.

Also the stop/start nature of comuting is a pain. A stop / start cycle to / from crusing speed takes about as much energy as up to 300m travel. This is another reason why undulating cycle lanes on paths can be nearly unusable compared to the flat smooth surface road users get. Also cycle lanes should be taken as far away from roads as possible so you don't have to put with the noise etc. Most away from the road paths in Dublin that have a suitable surface for cycling seem to prohibit it.

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rubadub

0.15 calories? sounds very little , that means a man of 80kg only uses 12kcal per km? A tin of beans is about 250kcal so that is 21km of cycling to work off a light snack.

I presume this is without stops & starts though that would add hugely.

Lennoxschips

that depends on whether you consider a tin of beans a light snack

rubadub

Lennoxschips wrote:

that depends on whether you consider a tin of beans a light snack

beans can give a turbo boost with their added wind power!

Seriously though thats 100km cycle to work off a chinese takeaway.

randomname2005

It also depends on what you mean by a calorie! Sometimes kcals are cals. From howstuffworks.com:
Most of us think of calories in relation to food, as in "This can of soda has 200 calories." It turns out that the calories on a food package are actually kilocalories (1,000 calories = 1 kilocalorie)

and living in Ireland means there are very few flat roads!!!
R