But how many calories does it take to get the oil out of the ground, transport it, refine it, and then transport the gas to your local filling station? Bikes come out ahead if you consider the costs of producing BOTH types of fuel, beef and gas.

You make a good point but your assumptions are not quite correct. According to my data it takes 1.36 units of crude oil to make 1 unit of gasoline so, taking into account this conversion loss and energy consumption, we get 1,550 x 1.36 = 2,108, which is still less than the beef-powered cyclist (albeit a bit closer, narrowing the gap to 132). Can anyone else think of anything missing on either side of the analysis?

These are very interesting observations. I take it as more of a statement to encourage vegetarianism rather than drive a car. I worked out once that driving my car used about 62 times as much energy as riding my bike, which is only off by a factor of 2 from your comparison.

In terms of practicalities, I'll point out a couple things so people don't go storing their bikes right away!

First of all, you'd be hard pressed to find a cyclist (an avid one) who is on the Atkins diet. While some energy may come from beef, a good fraction will come from rice, wheat or potatoes (which all do in fact require some fossil fuels, as does broccoli). These other foods likely use much less fossil fuel to generate.

Also, most people who ride a bike on a regular basis, like as a bike commuter (this is where people can have the biggest impact in terms of fossil fuel use), will tend to ride at a comfortable pace, unlike someone on a recreational racing ride who might ride more aggressively. At a comfortable pace, I suspect they use less than 64 calories per mile. But this will vary a lot per person.

And finally, as the Harpers article points out, you may have choices as to where your meat comes from, and how it was grown. If it is localy produced, at the very least you're cutting down on shipping fuel consumption.

Here's a link to my not so scientific comparison.

Thank you Darren! I think everyone understands that this week's analysis is aimed at confirming or busting of a silly myth. You would have a lot of trouble trying to find someone that gets 100% of their calories from corn-fed feed-lot cows, and even more trouble finding such a person that also rides a bike. Therefore I would not advocate driving over cycling to anyone, not even the most carniverous amongst you. But, if you must eat meat, I would advocate a balanced diet that includes local/seasonal vegetables and meat from animals that are not raised on a corn diet.

What do the folks at Niman Ranch have to say?

I think it was John Robbins (son of the ice cream magnet, he became an advocate of vegetarian diet) who said that eating a one pound steak uses the same amount of petrochemicals as driving 25 miles.

His point was not that we should drive more but that eating low on the food chain is underestimated as a path to oil conservation, not to mention water conservation and reduction of pollution from factory farming. Furthermore, in a hungry world, an acre can feed more people if they eat vegetable protein than if they eat animal protein.

To get an accurate result, you also need to add the number of calories the driver's body burns. That is, a driver burns calories too -- just not as many -- as a cyclist.

What does the driver eat? To be fair, I think the driver must also eat beef.

Eating meat may not be the only issue. I suspect that chickens convert feed into meat much more efficiently than cattle. A friend of mine keeps and breeds meat rabbits in his backyard. Transport cost is eliminated and the main energy input, apart from grass and kitchen scraps, is the pellets he feeds them.It is nutritious lean meat and comes with a fairly low energy cost. It's better to be vegetarian but not all meats are the same.

Though it's somewhat peripheral, the methane produced from cow farts, petroleum processing, and fossil=fuel burning should be factored into this issue. Consider: How much methane does a bicyclist rider produce? Compare that figure (it must be close to zero) to the other sources.

Hi Pablo, Nick, et al-- thanks for bringing this up. I've become really interested in sustainability metrics lately, not because they're accurate so much, but because at least they represent an honest attempt to figure out how 'sustainable' current lifestyles are. Calculating them is a lot more intellectually respectable than just standing on some principle (e.g. "food X is bad") and trusting that it will lead to the right conclusion.

Recently I played with an ecological footprint calculator to compare two "progressive" lifestyles and discovered that (according to the calculator) neither was even close to sustainability. Not sure whether to find a new calculator or give up and order a McMansion and a Hummer, but at least it got me beyond propaganda and in to the nitty gritty.