http://www.6footsix.com/my_weblog/2008/06/extreme-mileage.html

now if she could only find a bike that would fit…

Contrast an ice cold bike to a car. Each car controls literally thousands of explosions under the hood every minute and burn hundreds of Calories when you floor it (maybe 750 Calories in an average car if you floor it for a quarter mile). The brakes get wildly hot, and the dampers get so hot you can’t touch them. Cars can stay hot for an hour or two after you drive them.

I just wanted to know how the energy usage of a rumbling car compared to the my lovely gliding road bike. Don’t get me wrong, I love cars, but the more I ride, the more I see the merits of riding, both for me, and for citizens of our country.

@ Sue: Yup! (although we’re talking kilocalories, or “Calories” with a capital “C” here—they’re the same Calories that you are used to eating—100 Calories in a slice of bread, for example.

And you’re right the production costs of food can vary—you could eat lettuce air-freighted from across the world, or toss a few seeds in your back yard and eventually pick the apples that spring up—for free. I don’t really have a good idea how much the costs for supermarket food is. I suspect the production costs of certain foods vary dramatically from season to season.

@ Gary– Thanks! You’re absolutely right- people do indeed have a “maintenance energy expenditure”—it is called the “Basal Metabolic Rate” and it is the energy you use, basically, to stay alive. You can think of it as the number of Calories you’d burn per hour if you were sitting still in the dark.

The heart rate monitor I used (a Polar F11) was measuring energy expenditure above my BMR; unless my heart rate rose above my “resting heart rate,” my HRM recorded my instantaneous energy expenditure at 0 Calories / hour.

So you’d think that the eventual result of the experiment, “633 mpg,” would be a good number to compare to a car’s “miles per gallon.” However, I’ve read on various forums that Polar’s heart rate monitors overestimate Caloric consumption by as much as 50%, which would mean that my actual efficiency may have been as much as 945 mpg.

At steady state, a car’s main enemy is drag, not weight; so additional passengers are relatively “inexpensive.” If a suburban is getting 12 mpg and you fill it with 6 more people, it is still going to get nearly 12 miles per gallon (say 11 for the sake of argument). That means it gets 12 “passenger miles per gallon” one-up, but 77 “passenger miles per gallon seven-up—just something to think about. One person driving a 40 mpg Prius isn’t that efficient (although four-up a prius gets 160 “passenger miles per gallon”). A Greyhound bus gets 4 mpg, but if you stuff 40 people in it, you’re getting 160 “passenger miles per gallon”. Assume a little kid in a child-seat does little to affect the efficiency of a cyclist and that bicycle will be knocking on the door of 1300 “passenger miles per gallon”

@ Gabriel—wow, that’s a long commute- I bet you’re in great shape!

@ Mountain Bike Insurance –wow your name is Mountain Bike Insurance?

I couldn’t understand some parts of this article, but I guess I just need to check some more resources regarding this, because it sounds interesting….

According to world watch (http://www.worldwatch.org/node/4057), driving a car takes 1,860 [kilo]calories per passenger-mile; walking takes 100 [kilo]calories per passenger-mile; cycling a mile takes 35 [kilo]calories per passenger-mile (energy in, change in position of a mass out). If we ignore everything except the effect–moving one passenger one mile–we can estimate the relative efficiencies: a car is less than 1/50 as efficient, and walking is about 1/3 as efficient as riding a bike.

Thanks for the article!

Because a calorie is a calorie, and a pound is a pound, we should be comparing loads of equal weights as well. Then we can see if the human is more efficient than the Honda.

Also, someone mentioned the production and delivery costs of the food. What about production and delivery of gasoline? I’m pretty sure we can consider them equal for sake of argument.

Also, with added respiration and metabolism, the human body increases its output of CO2. So we should compare how much CO2 the body produces at rest, and in motion (relative to the weight of an average automobile). And we could find out if cycling is better or worse for greenhouse gases. Wouldn’t that be ironic?

Sue, regarding your comment about where the calories came from, production costs, etc. it’s a valid point. I would reply by pointing out that in a car you have no choice, they have to come from crude oil and exit your tailpipe as co2, nitrous oxides, etc. whereas on the bike you have a broad range of foods and food sources to choose from.

Nick, I hope you keep up the riding. I discovered the joys of human propulsion many years ago and ride to/from work over 55 miles a day. There’s a whole bunch of resources online, just google “car free” or check out http://www.bikeforums.net