Living Car Free - Bicycling Wastes Gas?

Most people think that bicycling doesn't use gas, but actually it does. It takes lots of fossil fuel to produce the food for the cyclist's calories -- and cycling requires more food fuel than driving.

Of course, we can't just stop eating, but we can definitely choose what we eat, and here's the kicker: meat requires much more fossil fuel to produce than vegetables and grains. How much more? About 145 times more for beef than for potatoes.1 The reason for this is simple: Cattle consume 14 times more grain than they produce as meat. They're food factories in reverse. So it takes a lot more water, land, and of course, energy to produce that meat. In short, the more meat you eat, the more gas you waste.

David Pimentel of Cornell University calculates that it takes nearly twice as much fossil energy to produce a typical American diet than a pure vegetarian diet. This works out to about an extra 150 gallons of fossil fuels per year for a meat-eater. This means that meat-eaters are "driving" an extra eleven miles every day whether they really drive or not, when we look at how much extra fuel it takes to feed them.2

In fact, meat production is so wasteful that walking actually uses more fossil energy than driving, if the calories burned from walking come from a typical American diet:

"It is actually quite astounding how much energy is wasted by the standard American diet-style. Even driving many gas-guzzling luxury cars can conserve energy over walking -- that is, when the calories you burn walking come from the standard American diet! (62) This is because the energy needed to produce the food you would burn in walking a given distance is greater than the energy needed to fuel your car to travel the same distance, assuming that the car gets 24 miles per gallon or better."4
The same is not true of bicycling vs. driving, because bicycling is more than twice as efficient as walking (calories consumed per distance traveled) -- bicycling uses less fossil energy than driving even if the cyclist were eating nothing but beef.5 But to focus on this misses the point. It's no bombshell that cycling uses less fossil energy than driving. What's important is that meat-eaters use twice as much fossil energy as pure vegetarians -- whether they're bicycling or not.

What does this mean in practical terms?

It means that the amount of gas you use isn't just related to how you get from place to place, it's also related to what you eat. Meatless diets require half as much fuel to produce than the standard American diet. Pimentel calculated that if the entire world ate the way the U.S. does, the planet's entire petroleum reserves would be exhausted in 13 years. The typical American could save almost as much gas by going vegetarian as by not driving.6

Food for thought.

Yes, this is precise why people shouldn't run around willy nilly making blanket statements about the detrimental effects of their actions, or the actions of others, without due consideration. What you're refering to with meat is know as the change in trophic level, and for each change you generaly incur a penalty. The rule of thumb is each change ends up losing ~90% of the initial energy, in the case of cattle this is ~95% compared to potatoes.

Figures some bozo from Cornell would come up with such research.

I grow my own food and kill my own meat.

Seriously- who really cares? The entire premise is partially based on the fact that farmers pay no FUEL TAX and have no real incentive to use energy-efficient farming practices. In the US, food is so cheap and plentiful that they literally can burn it as ethanol and biodiesel. And that is to manipulate crop prices more that it has to do with energy policy. At least here in Europe, we generally only grow food to eat (no soy beans or corn production--- rather vegetables, or hay for winter livestock feed).

Yeah--- I probably waste more water and electricity from showering more often because I bike.


When I was biking in the US-- commuting 40 miles round trip daily, I figured that I ate more money spent on extra calories for quality food than I would have spent on gas. Of course, with a vehicle, fuel is only a small part of car ownership. But I rode to work for health-- not for any other reason. Try putting a monetary value on good health and fitness.

This has nothing to do with lack of taxation for farm fuels, it has to do with the state of agriculture, specifically agribusiness. It's very fossil fuel intensive, and by raising animals to eat you're losing ~95% of your vegetables that you just spent tons of energy to grow in the first place. Obviously some situations are different, take chickens on the farm, because you can let 'em go do their thing, and as long as the chicks don't get picked off too much, there's a no hassle, low energy source of meat and eggs. Personally I'd just keep a few hens around and have eggs, having an embryo pop out of the egg and onto the frying pan, sizzling, is unpalatable. Health and fitness is worth $43.89.

- i don't know if i could totally give up on meat in my diet, but i do know what's the most expensive meat on the planet!

- and you'll need one of these (http://www.tikimaster.com/product/CLUB15) to eat it!

:-)

Now a-days peeing in the municipal toilet uses gasoline. That's why I...

Any veggies or veagans actually ride 50 or more miles a day? If so what do you eat?

I personally think that waste is what fun is all about. Why pedal fast, (and waste engergy), when you could just coast? What about sex, wouldnt it be less wasteful to just sit in the AC?

I'd be a vegitarian, but those combines kill thousands of field mice per acre. How sad.

I am on the verge of judging someone judgemental.

What if I post a preemptive judgement on your ass? Ohhhh... burn.
Damn I'm bored. :)

Figures some bozo from Cornell would come up with such research.

I grow my own food and kill my own meat.

Seriously- who really cares? The entire premise is partially based on the fact that farmers pay no FUEL TAX and have no real incentive to use energy-efficient farming practices. In the US, food is so cheap and plentiful that they literally can burn it as ethanol and biodiesel. And that is to manipulate crop prices more that it has to do with energy policy. At least here in Europe, we generally only grow food to eat (no soy beans or corn production--- rather vegetables, or hay for winter livestock feed).

Yeah--- I probably waste more water and electricity from showering more often because I bike.
Cattle production is a major cause of water pollution. In the United States, cattle produce nearly one billion tons of organic waste each year. It has been estimated that cattle and other livestock account for a significant percentage of pollutants in the nation's rivers, lakes, streams and aquifers. Raising cattle also requires vast amounts of water. Nearly half the water consumed in the United States is used to grow feed for cattle and other livestock -- while our precious stores of fresh water dwindle at an alarming rate.


When I was biking in the US-- commuting 40 miles round trip daily, I figured that I ate more money spent on extra calories for quality food than I would have spent on gas. Of course, with a vehicle, fuel is only a small part of car ownership. But I rode to work for health-- not for any other reason. Try putting a monetary value on good health and fitness.

This has nothing to do with how much money you spend. It has to do with how much fossil fuel is used to sustain a meat based diet.

This has nothing to do with how much money you spend. It has to do with how much fossil fuel is used to sustain a meat based diet.


I am familiar with water usage as it relates to agribiz.... I was just taking the example to its absurdist extreme. I guess I don't really have to shower... any more than I need to eat meat. ;)

This may be a good argument for vegetarianism, but its irrelevant to car vs. bike discussions. The idea that how much we eat is directly linked to how much we exercise is obviously incorrect. Follow the 300 lb guy in the SUV to the restaurant and then watch, with your steaming face plastered against the window, as he downs an entire sirloin steak. The calories used for driving are on top of whatever calories the driver consumes.

What about the greenhouse gases released by the vegan cyclist. Greater contribution than the H2!!

Isn’t the, “what is more efficient use of oil - meat or veggies”, really an argument against giant, geographically localized (and distant) agribusiness and animal farming both?

It must cost more to ship a watermelon from Georgia, then a chicken from Indiana.

I suppose that there is an oil problem with eating things that come from more than 20 miles away. In Pennsylvania, that certainly means that, Washington cherries, tufu from far away, and potatoes are a “waste” of fuel. Groundhogs, Turkeys, deer, Milk, turnips, rutabaga, and apples on the other hand are OK. Bunnies are easy to get most everywhere East, no gas needed.

http://www.bowhunting.net/susieq/rabbit.html

This may be a good argument for vegetarianism, but its irrelevant to car vs. bike discussions. The idea that how much we eat is directly linked to how much we exercise is obviously incorrect. Follow the 300 lb guy in the SUV to the restaurant and then watch, with your steaming face plastered against the window, as he downs an entire sirloin steak. The calories used for driving are on top of whatever calories the driver consumes.
Seriously, at least we're using that "fuel" to power our own mode of transportation rather than just enlarging our asses, thus further ensuring that we're gonna need to drive a car to get where we're going because we're too darn fat.

This topic belongs in Foo as it has NOTHING to do with being car-lite
or car-free. How much fuel is used in the production of anything is
a seperate issue from the use of cycles for personal transport.

That said, the focus of this poster on meat in our diet is nothing more
than a radical Vegan posting trollish statements that both annoy and
mis-reprsent the intent of the car less cyclist. It is also an insult to the
folk's who care enough on a personal level to peddle their way around
inplace of using MORE fuel with cars.

This may be a good argument for vegetarianism, but its irrelevant to car vs. bike discussions. The idea that how much we eat is directly linked to how much we exercise is obviously incorrect. Follow the 300 lb guy in the SUV to the restaurant and then watch, with your steaming face plastered against the window, as he downs an entire sirloin steak. The calories used for driving are on top of whatever calories the driver consumes.

+1

This is a pointless thread.

i've been doing some research on this topic for a while. did you copy and paste this from somewhere or are these your original thoughts? there are some citations in there, but no bibliography. where is this from?

Iirc it's based on a pimental paper and some other papers, you should be able to find different articles on the same thing through Google.

Iirc it's based on a pimental paper and some other papers, you should be able to find different articles on the same thing through Google.
OK but if you have any facts to back your argument that eating is bad, i'd like to see them. Otherwise, this is just another rant and troll.

Also, What about organic or sustainable agriculture?

I only eat veal raised by amish farmers, so its ok

^Well just so long as they're amish baby cows, I guess it's OK.^

^^^ I shouldn't really have to, since it appears that the original post was a copy from http://bicycleuniverse.info/transpo/beef.html

I'm quite familiar w/ the work of Pimental. He happens to present a relatively bleak view of agriculture. There are quite a few assumptions that have to be made along the way in these calculations, and he always makes the ones that make farming look poor. Two primary examples are how emissions are allocated to chemical by-products of the fertilizer industry, e.g. ammonia/co2 production, and what steps are required to make farming sustainable, e.g. replacing carbon in the soil. This brings us back to the definition of sustainability.

I'm not arguing w/ the idea that meat uses a lot more energy per kcal or per gram produced than vegetables, and especially more than grains.

When someone starts cycling in place of driving (say 10,000 miles a year), the need to eat a lot more. Most of the extra calories can come from grain, though. This is especially true if they aren't hammering, which is done for exercise rather than transportation. Any nutritionist will tell you that atheletes need a higher percentage of calories from carbs. So, most of the extra calories should come from dense carbs like potatos, rice, or pasta. This puts the assumption of fueling a biker w/ beef into context.

People that cycle 10,000 miles are also usually displacing other forms of excercise. If in the U.S., you might compare them to someone that drives to work, then drives to the gym, then eats a lot more b/c of exercise at the gym, then overeats anyway. Or, compare them to someone that is overweight and out of shape. Add in the environmental cost of all of the pills that these relatively unhealthy people swallow later in life. Add in the environmental cost of whatever they do in place of cycling (boating, wathing tv, driving to the park, etc.). This is of course getting quite nit-picky. However, the point is that the raw numbers need to be understood as quite imprecise. They can offer insight, but really only when one better understands how they are calculated. When comparing biking to driving, I believe that the real insight should be that cycling shifts the environmental burden from fossil fuel consumption to water use, eutrophication, and odor pollution. Exactly how much depend on all of tangentials brought up in this post and many of the previous posts by others in this thread.

Most people think that bicycling doesn't use gas, but actually it does. It takes lots of fossil fuel to produce the food for the cyclist's calories -- and cycling requires more food fuel than driving.



I started my 18 miles daily commute (9 each way) about I really DON'T eat more than I did 4 years ago before I started, and have heard the same from others.

Yogurt before leaving, mid morning snack, sandwhich for lunch and a normal dinner of my choice. In fact I would think biking forces you to make wiser food choice - i.e. not eating tons of food that would make you sluggish and feel physically unhealthy.

I think my body has completely adapted to my mon-fri ride. A few weeks ago I did a long bike tour (167 miles in two days). THEN I was eating like horse. 10 peanut butter and honey sandwiches at the rest stops, powerbars left and right, and lots and lots of water and gatorade -- but was the first time I've done a ride THAT long.

I'll bet an initial commuter would eat more food to compensate, but like me as their body adapted they wouldn't need as much. Does that make any sense from a phyisiologocal standpoint

Figures some bozo from Cornell would come up with such research.


You are the bozo for making such a statement.

How about someone with such an insanely high metabolism that he can easily consume 10,000 calories in a day and not gain an ounce, even when NOT biking or really doing anything specific for excercise? :p

When I was still in the Navy we counted one day when I had plenty of money for snacks and stuff.... I hit 10,000 calories by 1 PM. At that point we got pretty disgusted and quit counting. :roflmao:

I actually consume a lot less now than I did then, and I rode 650 miles last month, and didn't run my truck at all.

OK but if you have any facts to back your argument that eating is bad, i'd like to see them. Otherwise, this is just another rant and troll.

Also, What about organic or sustainable agriculture?

1)It ain't my argument that eating's bad. I never said eating's bad, I actually like to eat.
2)Go search google and read those papers, they contain "facts" that may or may not be accurate, judge for yourself.
3)I don't know about organic or sustainable agriculture, why don't you go find out for yourself?
4)Baa-Naa-Naa.

Hmmm. While it’s true that in this day and age eating means transporting food which means large fuel costs, and raising food also means large fuel costs (tractors and such), people will eat whether or not they live an active life style. Some people eat more when they’re active, some people eat less (I tend to get less hungry when I work out, for one), and many more don’t change their diet at all.

This means that while there is a slight increase, on average, of consumed fuel because of the people who bike to work, there is a considerable decrease, on average, because they are no longer expending that extra gallon of gasoline for every fifteen miles they commute (which is a reasonable average number of miles, I’d guess, that those who bike to work would otherwise have to drive). All in all, it’s better to bike to work. Besides all of that, the article needs to look at a few other things:

-People who are healthy through lifestyle get to spend less on medication and health care costs down the road. This saves on the manufacturing and transport cost of pills (and pills tend to have a lot more wasted space due to packaging then food) and medical equipment, not to mention ambulances and such.

-Biking to work means using less oil (bikes don’t consume the stuff nearly as much as cars do).

-Biking to work means using less rubber (bike tires don’t have nearly as much rubber as care tires do, and I’d imagine they last just as long).

-For most people, a steady diet of exercise helps to keep their stress levels down. Less stress means reduced medical costs, and means fewer long distance vacations (“I JUST NEED TO GET OUT OF HERE! AARRGH!”) – resulting in reduced gasoline usage, reduced oil usage, and reduced tire usage.

I’m sure there’s more, too, but I don’t feel like thinking about it at the moment.

Of course, we can't just stop eating, but we can definitely choose what we eat, and here's the kicker: meat requires much more fossil fuel to produce than vegetables and grains. How much more? About 145 times more for beef than for potatoes.1 The reason for this is simple: Cattle consume 14 times more grain than they produce as meat. They're food factories in reverse. So it takes a lot more water, land, and of course, energy to produce that meat. In short, the more meat you eat, the more gas you waste.

This assumes that cattle are fed a diet of conventional (non-organic) grains -- which, sadly, is most often true. Organic beef is better, because the grains are grown with much less fossil fuel (in the pesticides and fertilizer); grass-fed beef is better still. As far as I understand, grains are not a natural diet for cows or chickens.

If you don't know where you food is coming from, there's a good chance that it's wasteful.

I know a farmer who sells grass-fed free-range chicken, eggs, and beef -- fairly cheap, too -- at the local farmers' market. I don't currently eat meat, but if I wanted to, my conscience wouldn't protest if I bought meat from him. The local health food store also has several varieties of organic yogurt sourced within about 100 miles; one of them is apparently from grass-fed (or hay-fed) cows, and it's the cheapest one, too. It just takes a little bit of effort to look around, ask at the nearest farmers' market, read some labels, figure out where the food comes from and how it's grown, and then make your buying decisions with that knowledge -- causing (hopefully) less waste, making you healthier, and supporting the kind of farmers and farming practices (including, if applicable, animal treatment) you wish to support.

If you don't know any good local sources of meat or dairy, try searching here (http://www.eatwellguide.org/). It's not complete, but it's a start.

A vegetarian in a Ford Expedition (if there is such a thing) uses less fuel than a bicyclist who likes turkey sandwiches? Give me a BREAK. In my experience, people will eat roughly the same number of calories whether they exercise or not. And, judging by appearances, motorists, on average, eat quite a bit more than dedicated cyclists. Yes, going veggie is better for the planet. Cows go through a lot of grain and water, and they fart out a lot of methane, a potent greenhouse gas. And, you know, I even like tofu once in a while. But don't even THINK of slapping that turkey sandwich out of my hand. I'll give up birds and fish when motorists do. Let's be honest: it's just silly to argue that a person on a bike, on balance, uses more fossil fuel than a person in a big-ass 4WD pickup truck. Like that person is driving his F150 around, looking for a place that serves rice and broccoli with a nice herbal tea.

Sheeesh! calm down guys! The reaction from some of you kinda reminds me of the people who get offended by the carfree people telling them that driving is bad. Its really interesting how offended people get when you point out the implications of their own lifestyle.

Anyway, to clear something up (although I shouldn't have to), it doesn't say in the article that biking is less energy efficient than driving. It says that walking (which is less efficient than cycling) uses more fossil fuel than driving, if the person walking is eating the standard american diet (meat based diet).

Here, read it again:(if you read it at all)


The same is not true of bicycling vs. driving, because bicycling is more than twice as efficient as walking (calories consumed per distance traveled) -- bicycling uses less fossil energy than driving even if the cyclist were eating nothing but beef.5 But to focus on this misses the point. It's no bombshell that cycling uses less fossil energy than driving. What's important is that meat-eaters use twice as much fossil energy as pure vegetarians -- whether they're bicycling or not.

So bike on brothers and sisters! Beef eaters and vegans alike, rest assured you are doing the world a great service! No need to get all butt hurt about it.

So yes, biking is more efficient than both driving or walking.

Eating vegetables is more efficient than eating meat.

Eating organic is more efficient than eating commercial (especially if it is grown locally).

Tightwad posted:

This topic belongs in Foo as it has NOTHING to do with being car-lite
or car-free. How much fuel is used in the production of anything is
a seperate issue from the use of cycles for personal transport.

That said, the focus of this poster on meat in our diet is nothing more
than a radical Vegan posting trollish statements that both annoy and
mis-reprsent the intent of the car less cyclist. It is also an insult to the
folk's who care enough on a personal level to peddle their way around
inplace of using MORE fuel with cars.

How do you know the intent of the carless cyclist? I happen to be one of them. I didn't ask you to speak for me.

I have been carfree for years and I think this thread does belong here. I became carfee because I care about the environment (amoung many other reasons). I posted it because I thought some of you might care.Thats assuming that some of you became carfree for similar reasons (I know that not all of you did). Maybe if the meat and dairy/agribusiness wasn't so highly subsidizedyou might be able to understand the real cost of your diet.

it appears that the original post was a copy from http://bicycleuniverse.info/transpo/beef.html


Correct.

Since I was implicated, I might as well contribute something...

More than 10 kcalories (kilogram-calories or "large calories") of exosomatic energy are spent in the U.S. food system per kcalorie of food delivered to the consumer.
Source (http://www.dieoff.com/page69.htm)

If you look at a page like this calorie chart, you will find that a person riding a bicycle at 15 miles per hour (24 km per hour) burns 0.049 calories per pound per minute. So a 175-pound (77-kg) person burns 515 calories in an hour, or about 34 calories per mile (about 21 calories per km).

A gallon of gasoline (about 4 liters) contains about 31,000 calories.
Source (http://auto.howstuffworks.com/question527.htm)

For 2006, sedans, wagons and compacts are expected to average 24.6 mpg. SUVs are expected to get 18.5 mpg and pickups 17 mpg.
Souce (http://money.cnn.com/2006/07/18/autos/fuel_eco_trends.reut/index.htm)

So, if I'm driving a car that gets ~25mpg, then I'm using 31,000 calories per 25 miles. On a bicycle I use ~34 calories per mile, or 850 calories per 25 miles. However, each calorie of food requires 10 calories of fossil fuels, so I'm using 8500 calories of fossil fuels to go 25 miles. But wait, there's more. A car will get ~25mpg at around 70mph, if that same car went 15 mph, it would get someplace north of 100mpg. Why? Because drag increases with the square of the velocity, so a car going 15mph is using ~1/20th of the energy a car moving at 70mph uses to overcome fluid drag. Now since rolling resistance and pumping losses play a huge part at low speeds for most cars (gassers, diesels don't suffer from pumping losses) you won't actually see 500mpg, you'll see ~100-300mpg depending on what gear you're using at 15mph, i.e. what your pumping losses are, so at 100mpg a car is actually using less energy from fossil fuels, 7750cal, than the average cyclist is, 8500. Otoh, if that cyclist is a vegetarian then the fossil fuels used in their diet are probably closer to 1 calorie of fossil fuel, to 1 calorie of food, so they may only use ~850 calories per 25 miles. Much less than a 25mpg gasoline powered car. Much less than any car? Maybe not. Lets take a look at Volkswagen/Audi's 3L Lupo/A3, which gets ~80mpg combined, and ~120mpg@55mph.

I too drive the Audi A2 3L in Britain. I'm based in South Yorkshire and am currently averaging 96.3mpg including town work. I can easily top 100mpg on long trips and acheived an incredible 120.2mpg on a door to door trip from Doncaster to Uxbridge, which required a cruising speed of around 55mph down the M1 and M25.

The 3L refers not to engine size but to the fact that it is designed to use just three liters of fuel per 100 kilometers - about 78 miles per gallon.
Source (http://www.greencarcongress.com/2005/04/vw_abandons_its.html) Source (http://www.usatoday.com/money/consumer/autos/mareview/mauto497.htm)
Since these are both diesels they do not suffer from pumping losses, they probably get ~1000mpg at 15mph, diesel fuel has more energy, so there're probably ~36,000 calories for each gallon of fuel, so if they get 1000mpg@15mph they use 900cal of fuel to go 25 miles. About as good as a vegetarian cyclist. And since the vegetarian cyclist has a 1to1 fossil fuel to food calorie ratio, we know the cyclist uses ~ as much energy to move themselves as someone in a 3l Lupo/A3 going 15mph does. The cyclist is obviously much smaller, so why is the cyclist so inefficient?
Well, the cyclist has tons of aerodynamic drag, so much so that an atb/rider's CdA (the product of the drag coefficient and reference area) is .79m^2, while a Honda Insight has a CdA of .48m^2, less than the bike.
Source (http://damonrinard.com/aero/measuring.htm) Source (http://www.escortradar.com/metricsupplement.pdf)
Otoh, it's obvious that the bike has much less drag due to friction from the road to move at 15mph compared to the car. Why? Because the car is ~2000lbs and the cyclist is ~200lbs, so this is in the bikes favor. Oto,oh ;), a human probably isn't as efficient as an efficient diesel engine at doing work related to moving a vehicle... So, when all's said and done, the average cyclist and efficient car need ~ the same energy to go 15mph. But what if we have an aerodynamic bicycle, well then the energy once again swings back to favor the cyclist because the velomobile can have minimal reference area, etc...
So, in summation.
-Eat your vegetables.
-A device functions based on how it's built.
-Pick the right device for the job, if the right device doesn't exist, build it.
-Stop playing the blame game and start figuring out what you can do for the issues you care about. You may not be able to change others, but you can change yourself.
-Insert lame phrase here.

P.s. Yes, I know, you eat a certain amount of food regardless of whether you bike, etc...
I've met a few people that can regulate their caloric intake, maybe you can try. If it doesn't work, then yes, you might as well put it to good use, blah, yada...
P.p.s. Varna "Diablo" (http://www.wisil.recumbents.com/wisil/whpsc2001/varna_detail.htm) says what? Damn. (http://www.easyracers.com/videos/BM_2004.wmv)

Damn good and thorough breakdown, thanks!

Np! :D

I completely support the idea of this thread. I think people tend to move an inch and think that's all there is. It reminds of the people rich enough to buy a hybrid car who think they're saving the world. Those people never want to hear about how little difference it will actually make. Bicycle commuting is a by and large an improvement, but if we want to do something about global warming or dependence on foreign oil, there's so many more avenues that are capable of accomplishing something far more.

if that same car went 15 mph, it would get someplace north of 100mpg.

Nope. And no, that 78mpg diesel won't get 1000mpg driving 15mph either.

American cars get worse gas mileage as speed decreases below 45mph or so because they have big, heavy engines that have 20 times the horsepower they'd need for maintaining speed on flat ground at 65 mph. We're talking about a very large vehicle weighing thousands of pounds which is also pretty aerodynamic.

Losses from friction in those large engines while they spin at 1000+ revolutions per minute eat up any improvements you would see to gas mileage when moving slowly.

Now if somehow you could run those engines at 60 RPM with the same efficiency as you can at 4,500 RPM (which is about where their efficiency peaks- meaning you're using a good 70% or so of the engine's horsepower) then you could get wonderful gas mileage at 15mph using less than 1% of the vehicle's horsepower.

I thought we were insulting the american diet. Let's use american cars for gas mileage, then. I don't want to hear any more mention of 70-100mpg diesels in this thread. No car bought in america gets 120mpg at 15 miles per hour.

More importantly, this thread makes the assumption that the average car driver in America eats less than the average bike commuter, and I'm not sure that's a reasonable assumption to make.

I completely support the idea of this thread. I think people tend to move an inch and think that's all there is. It reminds of the people rich enough to buy a hybrid car who think they're saving the world. Those people never want to hear about how little difference it will actually make. Bicycle commuting is a by and large an improvement, but if we want to do something about global warming or dependence on foreign oil, there's so many more avenues that are capable of accomplishing something far more.
+1

I agree, lets stop driving to the big box stores in our single digit mileage SUV's, buying cheap, imported (transported ungodly distances using oil) disposable plastic (made from oil) crap, throwing it out then doing it all over again next week. It is going to take more than one single item or person to make the difference, it is going to take Everybody. FWIW NC DOT just released a Study (http://www.wral.com/news/9558337/detail.html) done in the Triangle area (Raleigh, Durham, RTP) that shows that the average commute was 27 miles and that the average driver made 10 trips a day. 95% of them never used public transit, and probably won't. It is going to take a major shift in attitude to make the necessary changes.

Aaron:)

Nope. And no, that 78mpg diesel won't get 1000mpg driving 15mph either.
Yes, if you could get that kind of mileage, a few people would drive that slow in order to save money. They'd drive over on the right hand edge of the roadway so that cars could pass them. This would be known as "Bicycluar Driving".

Re: my comments on gas mileage for regular cars sold in north america...

so a car like the honda civic gets pretty bad mileage at 15 mph, but if you totally redesign the vehicle, look what it can do:

http://www.physorg.com/news70040977.html


3,145 miles per US gallon

I bet that's a racetrack fuel economy figure, though. Add uphills, downhills, starts and stops, and I doubt that's possible.

I completely support the idea of this thread. I think people tend to move an inch and think that's all there is. It reminds of the people rich enough to buy a hybrid car who think they're saving the world. Those people never want to hear about how little difference it will actually make. Bicycle commuting is a by and large an improvement, but if we want to do something about global warming or dependence on foreign oil, there's so many more avenues that are capable of accomplishing something far more.Its not that people are unsympathetic to the other avenues -- its the misleading way its presented. Look at the title: "Bicycling Wastes Gas?". Its the implication that cyclists in particular are doing something wrong that is so irksome. Its the kind of thing/title that people who only drive will see, memorize, and taunt their cycling friends with. It doesn't really support cyclists who already have to deal with the roads cluttered with oversized vehicles.

In terms of the larger argument, if meat production is so dang inefficient, why is it that you can frequently spend more for a pound of tofu than a pound of meat? (Or at least I could before I started making my own). My hope is that these price inequities will straighten themselve out as oil prices increase. When the population hits 12 to 16 billion (possibly as early as 2050) nearly everyone will be neo-vegetarian due to constraints of arable land and energy.

When the population hits 12 to 16 billion (possibly as early as 2050) nearly everyone will be neo-vegetarian due to constraints of arable land and energy.

Fixed it for you.

And they're already pretty far along in growing beef in labs, so feh. Arable land will become a necessity of the past, and energy constraints will make people more willing to try things like wave generators, or nuclear power.

Nope. And no, that 78mpg diesel won't get 1000mpg driving 15mph either.
Explicitly speaking, I'm comparing it to the report of ~120mpg@55mph. Now as I'm sure you're aware, diesels do not suffer from pumping losses, so they're ~ as efficient at idle as they are at 2000rpm as they are at 4000rpm. If anything, diesel or compression ignition fuel efficiency is dependent on engine type (idi versus tdi) injection pressure (the faster the injectors can shoot fuel into the cylinders at tdc, the more efficient combustion is) and fuel to air ratio (as you lean the engine out, odds are, more fuel will combust). Anyway, where was I? Oh, yes, since the engine is for all intents and purposes just as efficient at all rpm, we can compare what the car gets at 55mph (120mpg) to what it would get at 15mph (?mpg).
Now since we're just going on the back of the envelope, we'll assume approximate steady state conditions, no wind, dry clean asphalt, no change in potential energy, etc... such that we're left with a car driving down a highway with ~0% grade. We have three sources of friction, rolling friction, sliding friction, and fluid friction. Rolling friction (http://en.wikipedia.org/wiki/Rolling_friction) depends on the car's weight, and the coefficient of friction between the car's tires and the surface they're on. On flat ground the normal force is the weight, so for all intents and purposes the force due to rolling friction is W*Crr, where W is the weight, and Crr is the product of the RR value of the tire, and the coefficient of the surface. Then we have sliding friction, since our tires aren't ideal, and slip, with the amount of slip increasing with speed. If you really want accuracy, you rig up an experiment, get a data set for that tire (we already know what the rolling friction is, so all we're left with is sliding friction) and thanks to the Stone-Weierstrass theorem we can find a polynomial equation that approximates that function as closely as we want to (not really, unless it's continuous). This approach is usually used with vehicles where the friction from the road is closer to the friction from the air (e.g. 80,000lb semi trucks with the CdA of a H3). One approximation I've seen for automobiles, and that I usually use, is the force from sliding friction is (10^-2)*Crr*V*W, where V is the velocity. Lastly, we have fluid friction (http://en.wikipedia.org/wiki/Drag_equation), which is (.5)(ro)(V^2)(CdA), where ro is the air density (I assume sea level), and CdA is the Cd of the vehicle times the reference area. Now, we plug and chug, and find out that at 15mph the friction from the road is ~22N, and at 55mph it's ~34N. Not a whole lot. The force used to overcome fluid drag however, is much higher (this is why it's so hard to go over 15-25mph on a bike) when we go faster because it depends on the square of velocity. In this case, at 55mph we need 567N to overcome fluid drag, and at 15mph we need 42N to overcome fluid drag. All told, we need ~nine times more enegy to go 55mph versus 15mph, and consequently will get something close to nine times the mileage we get at 55mph (~120mpg), so ~1000mpg, give or take a couple hundred mpg. If you have any more information on the sliding friction that'd be great! :D


American cars get worse gas mileage as speed decreases below 45mph or so because they have big, heavy engines that have 20 times the horsepower they'd need for maintaining speed on flat ground at 65 mph. We're talking about a very large vehicle weighing thousands of pounds which is also pretty aerodynamic.
You're refering to the increase in pumping losses in gasonline engines when building larger, higher hp engines. Well, yes, and this is why the gasoline powered car will only get ~100-300mpg at 15mph, even though we only need about a tenth of the energy to go at 15mph versus 55mph, engine efficiency is only a third or a fifth (or whatever) of what it might be at higher rpm, we can however sidestep this by putting the car in a gear such that we're as close to maximum torque as is practicable.
Pumping losses occur in gasoline engines because the intake can't open all the way at lower rpm (if it did we'd see big boom), so the cylinder pressure is much less (near vaccum) than it could be, and as such does negative work. When a gasoline engine's valves are wide open (maximum torque) and it's sucking in enough air so that the pressure reaches whatever the atmospheric pressure is, then it's only ~10-20% less efficient than a diesel. However, as rpm drops off, pumping losses increase and efficiency decreases.
Now to get around this, there is a technique use to maximize efficiency and minimize losses due to traveling too fast. It's suggested when you're low on gas to turn off the engine until you hit ~10mph, then turn it on and accelerate near full throttle (but not at, we don't want to enter open loop mode) until ~30mph, then shut off the engine until we again hit 10mph, wash, rinse repeat. But acclereating quickly we are minimizing pumping losses, and by driving between 10mph and 30mph we are getting the benfits of averaging ~15-20mph, without the pumping losses the engine might have at low rpm in the associated gear. Suposedly this was done as far back as the 50's, with drivers getting over 100mpg in cars that got 10mpg at highay speeds, I'll see if I can dig up the link once I get back from the store.

Edit- Found it (http://www.cleanmpg.com/forums/showthread.php?t=1207).
Edit2 - I was wrong about being wrong, based on the previous link, and this link (http://www.cruisinwithollie.org/Motor%20Tour%20CWO.htm).

17.25 mpg: It was no chore at all to get this healthy figure from the Golden Hawk. We drove as we thought most drivers would under ordinary conditions. We used Overdrive on the highway, but not in town; took off and stopped smoothly but without undue caution, and did not coast. Our windows were open because it was warm, and we played the radio when we felt like it.

19.67 mpg: For the small margin, we had to sweat this one out. Up went all the windows (Lowers aero drag of course!), the Overdrive button was firmly pushed in and remained there, making possible some coasting below cut-in speeds. The Radio stayed off. As soon as the engine caught, we took off. We drove far ahead of ourselves, making use of the brake or other sudden moves of any kind unnecessary. We cultivated a feather-light foot on the gas. In short, Economy Run driving takes all your attention, stern self discipline, and is no-fun. What price a 2-1/2 MPG saving? Yet there is one Economy Run tip on which you can’t lose, whether your interest is in economy, safety, or just being as skillful a driver as possible: that’s watching the road ahead, terrain, and other cars included. Not only will your mileage improve; as your new technique becomes habit, you will find you enjoy driving more. So will your newly relaxed passengers!

41.59 mpg: This was easier to achieve than the 19 MPG . Here’s how to do it. With the transmission in high gear, accelerate with the throttle floorboarded to 25 mph. Then simultaneously turn off the ignition and push in the clutch. When the car’s speed has dropped to 5 mph again, turn on the ignition and start the engine by popping the clutch. Down to the floor goes the accelerator, and you’re off again!

An important part of this strange procedure, understandably enough, is to have the tires inflated to high pressures. Although we used a mere 45 psi, the originators of the method went as high as 110. The tricks we used might be of help if you found that you were running out of gas far from civilization. The antics of the men that who ran the original Shell Wood River Mileage Marathon were weird and wonderful, and netted them as high as 158.36 actual MPG. They have, however, no practical value.

Some engine tuning was done, naturally, but it pales in significance before the other harsh measures. Here are some of the gimmicks used: Oversized tires with the treads filed off; extra high rear axle ratios; +SAE 10 lubricant in transmission, differential and front wheel bearings, planed cylinder heads to raise ratios very high; and disconnected fan belts. Combined with the very curious method of driving, they did the trick.

The jewel of the museum is a specially modified 1924 Chevrolet roadster. It sits in the center of the museum and was certainly a center of attention Saturday morning. This roadster is not built for speed, although it looks like it could have been a racing car. Painted Shell yellow, with a large number red #24 on each side it immediately attracts your attention. This little jewel’s claim to fame is that approximately 50 years ago it broke the Shell Mileage Marathon record with over 168 miles per gallon. This record stood until 1966. The first thing everyone wanted to see was the engine. After much prodding museum volunteer Bill Carr removed the bonnet so everyone could check out the engine. The museum is open on Wednesday and Thursday from 10:00 AM to 4:00 PM. Special tours may be scheduled by calling 618-255-3718 during regular museum hours.


Losses from friction in those large engines while they spin at 1000+ revolutions per minute eat up any improvements you would see to gas mileage when moving slowly.
It depends, does the increase in torque (efficiency) outweigh the reductioning in efficiency from the engine spinning faster? Well, that depends on the engine... If it has variable valve and ignition tehnology then it will reach ~ peak torque/efficiency and stay there from ~2k-4/6krpm, but older motors have more linear increase in torque with engine rpm. Take this newer BMW (http://www.cleanmpg.com/forums/showthread.php?t=1317), by cruising at a higher rpm, the fuel efficiency decreased by a few mpg. However, on my older, non-variable valve/ignition camry, when cruising at 75mph versus 60mph, my fuel economy only drops ~30%, even though I'm using ~80% more energy because when going from 2-3krpm, my engine efficiency is increasing, I can also cruise in third gear versus fourth and see a couple mpg increase. This is also why people these days experience more fuel economy shock when driving new cars. In the olden days, the increase in engine efficiency would mask the increase in energy required to go faster, but now that most engines are able to optimize efficiency at a much lower rpm, someone going 75mph versus 50mph (EPA highway testing cycle) will see a bigger chunk taken out of their fuel mileage, a bigger difference so to speak.


Now if somehow you could run those engines at 60 RPM with the same efficiency as you can at 4,500 RPM (which is about where their efficiency peaks- meaning you're using a good 70% or so of the engine's horsepower) then you could get wonderful gas mileage at 15mph using less than 1% of the vehicle's horsepower.
Well, that'd be great, but then you limit power, I'm content with eliminating pumping losses by driving a diesel. In my diesel bunny, I pull 45mpg city and 50mpg hghway because I don't see those pumping losses in the city that gasoline powered cars do.

@cerewa, they're minimizing frontal area and drag coefficient, while gearing the small gasoline engine to run at maximum rpm at test course speeds (~15-25mph).

You're refering to the increase in pumping losses in gasonline engines when building larger, higher hp engines. Well, yes, and this is why the gasoline powered car will only get ~100-300mpg at 15mph, even though we only need about a tenth of the energy to go at 15mph versus 55mph, engine efficiency is only a third or a fifth (or whatever) of what it might be at higher rpm, we can however sidestep this by putting the car in a gear such that we're as close to maximum torque as is practicable.


You throw out a lot of fancy numbers earlier in your post, and yet they don't seem to be related at all to real-world situations. Explain to me why anything you're saying is important if none of it is true.

Fixed it for you.

And they're already pretty far along in growing beef in labs, so feh. Arable land will become a necessity of the past, and energy constraints will make people more willing to try things like wave generators, or nuclear power.
Oops. Sometimes my brain thinks one thing and my fingers type another. Fixed it in my post.

Pretty sure things like "lab grown beef" were in "Profiles of the Future" and/or similar books going back 50 ~ 60 years. Whenever technologies take that long to develop, I figure that there are inherent problems that may never be overcome. Nuclear fission creates wastes that last 10 times longer than humans have been living in cities. Nuclear fusion is 50 years away and always will be. The only sure-fire way to live sustainably on the planet without destroying it is to live within our means. That means conservation, which seems to have become a dirty word in the U.S.

Oops. Sometimes my brain thinks one thing and my fingers type another. Fixed it in my post.

Pretty sure things like "lab grown beef" were in "Profiles of the Future" and/or similar books going back 50 ~ 60 years. Whenever technologies take that long to develop, I figure that there are inherent problems that may never be overcome. Nuclear fission creates wastes that last 10 times longer than humans have been living in cities. Nuclear fusion is 50 years away and always will be. The only sure-fire way to live sustainably on the planet without destroying it is to live within our means. That means conservation, which seems to have become a dirty word in the U.S.

I never said, "without destroying it".

Sustaining 16 billion humans on this planet is not possible forever. I assume that we will eventually kill off this planet, and move. There is no sure-fire way to live sustainably on this planet unless you can convince people to stop procreating.

Nuclear waste is a problem, but it's not one we have to deal with directly. It can be buried pretty effectively. Eventually, perhaps it can be removed from the planet entirely, something we can't feasibly do right now.

Why are you so cynical about the future of technology?

What's important is that meat-eaters use twice as much fossil energy as pure vegetarians -- whether they're bicycling or not.

The title of the thread really caught my attention as complete BS, but after reading through it, I realize that the thread drives in a complete different point, namely the quote above. I really enjoyed some of the facts listed and will follow up on those sources. I guess this proves that sometimes it's good to use flame bait to encourage others to contribute quality material :)

The thread title should really read: "Bicycling WASTES gas! (read fine print below)"

I'm sure this has been brought up before in the car-free forum, but what about the 100-mile diet (http://www.treehugger.com/files/2006/04/100_mile_diet_m_1.php)? Granted, this is not practical nor profitable from an agricultural/business point of view, but it is doable by those in certain regions. I live in the Bay Area and I've brought up the idea with my friend before.

You throw out a lot of fancy numbers earlier in your post, and yet they don't seem to be related at all to real-world situations. Explain to me why anything you're saying is important if none of it is true.

Fancy numbers? Where, in my last post, or the post before that? In my last post all I had were a couple tried and true formulas from physics and some common knowledge about internal combustion engine design. In the post before that, the only number that's not generally agreed with was the 10-1 calorie of fossil fuel per calorie of food, not beause it's wrong persay, but because it's not something many people look at, everything else's basic physics to the best of my knowledge. The equation I picked up (the one that involves rolling frictin, sliding friction, and fluid friction) is elaborated upon in this (http://www.cert.ucr.edu/research/pubs/Diesel_Vehicle_Fuel_Consumption.pdf) paper, and as you can see, they mention Faero (fluid friction), and Froll (rolling and sliding friction) as the road load parameters. The entire expression, or whatever approximation you're using seems to be called the road load force equation. From this we can see that aerodynamic drag increases with the square of velocity, and it quickly requires a lot of force to overcome. If you'd like a nice demonstration of how much drag influences energy and ultimately maximum speed, run some coast down tests on ~ flat ground from 20-15mph, and 5-0mph, in similar weather conditions and the same grade on your bike. You should notice a huge difference in the rate you slow down even though you're only slowing down 5mph in both cases. Ultimately, it's up to if you choose to believe anything, but blindly disbelieving something is just as bad as blindly believing something, at the very least you should make an attempt to prove or disprove something, for yourself more than anyone else. In any event, just to drive home the whole double your speed, quadruple your energy, here's a nice quote from wikipedia (which isn't the say-all, end-all, be-all reference).


A car cruising on a highway at 50 mph (80 km/h) may require only 10 horsepower (7 kW) to overcome air drag, but that same car at 100 mph (160 km/h) requires 80 hp (60 kW). With a doubling of speed the drag (force) quadruples per the formula.

I don't know--the numbers are impressive, but when I think visually, I get a different picture:

The 500 to 1000 extra calories that a cyclist supposedly needs would easily fit into a water bottle, assuming it's in the form of grain (which is mostly what we eat that's "extra"). How much fossil fuel does it take to produce and transport a water bottle full of dry pasta or brown rice? I think not very much. And I think if it's produced organically, food production is sustainable.

Then compare it to the 2 or 3 water bottles full of gasoline that the cyclist would use if driving. That is not sustainable, by any deinition.

The real problem we always run into is the definition of "sustainable." Agriculture and even industry can indeed be sustainable, by certain definitions of the word.

Fancy numbers? Where, in my last post, or the post before that? In my last post all I had were a couple tried and true formulas from physics and some common knowledge about internal combustion engine design. In the post before that, the only number that's not generally agreed with was the 10-1 calorie of fossil fuel per calorie of food, not beause it's wrong persay, but because it's not something many people look at, everything else's basic physics to the best of my knowledge. The equation I picked up (the one that involves rolling frictin, sliding friction, and fluid friction) is elaborated upon in this (http://www.cert.ucr.edu/research/pubs/Diesel_Vehicle_Fuel_Consumption.pdf) paper, and as you can see, they mention Faero (fluid friction), and Froll (rolling and sliding friction) as the road load parameters. The entire expression, or whatever approximation you're using seems to be called the road load force equation. From this we can see that aerodynamic drag increases with the square of velocity, and it quickly requires a lot of force to overcome. If you'd like a nice demonstration of how much drag influences energy and ultimately maximum speed, run some coast down tests on ~ flat ground from 20-15mph, and 5-0mph, in similar weather conditions. You should notice a huge difference in the rate you slow down even though you're only slowing down 5mph in both cases. Ultimately, it's up to if you choose to believe anything, but blindly disbelieving something is just as bad as blindly believing something, at the very least you should make an attempt to prove or disprove something, for yourself more than anyone else. In any event, just to drive home the whole double your speed, quadruple your energy, here's a nice quote from wikipedia (which isn't the say-all, end-all, be-all reference).

What I meant was that no matter how obvious and technically correct your formulas are, they're obviously not applicable in a normal situation. Otherwise, why would my gasoline truck get 25mpg on the highway at 70mph and 25mpg at 40mph highway driving? My engine runs at the same RPM at both those speeds, but according to you, I should be getting much, much higher mpg at 40 than at 70. I can assure you 100% that if I put my truck in first and drove at 15mph (so it will be at the peak of its torque range), the mileage would not be good.

What I meant was that no matter how obvious and technically correct your formulas are, they're obviously not applicable in a normal situation. Otherwise, why would my gasoline truck get 25mpg on the highway at 70mph and 25mpg at 40mph highway driving? My engine runs at the same RPM at both those speeds, but according to you, I should be getting much, much higher mpg at 40 than at 70. I can assure you 100% that if I put my truck in first and drove at 15mph (so it will be at the peak of its torque range), the mileage would not be good.

Are conditions exactly the same when you're going 40mph versus 70mph? Is there any difference in weather, grade, or traffic (Are you using the brakes)? The only way to absolutely, positively, tell for sure is to pull down a round trip journey to and from the same gas station of ~200 miles driving at 40mph, and 200 miles at 70mph, straight line, no large deviations in speed, the same weather, the same number of stops and shut down the engine at each stop longer than a few seconds. Hopefully you can find a very lonely four lane highway, set the cruise control, and do a 200 mile round trip (make sure to time yourself to verify your speedo is accurate, gps is even better). Until you do that there's just too much noise to really tell for sure. Also, there might be something odd popping up, like transmission efficiency in different gears, etc... Hell, I'm not sure if transmission losses are different from gear to gear. I just know that I get about the same mileage (5mpg difference) traveling at ~35-40mph in the city and 55mph on the highway because even though I'm traveling slower in the city, I have to stop for lights, slow down for turns, etc... which wastes energy, but I don't get much better highway because I'm going 55mph versus 35mph and have to use over twice the energy. Roughly speaking, the energy I waste braking is ~10% more than the energy I waste driving at 55mph, and if you look at a the city mileage of a hybrid like a prius, versus a normal car with a similar engine, like the corolla, you can see that the prius gets nearly twice the city mileage the corolla does, and the prius doesn't capture and use all the energy lost in braking, just a significant portion of that., so driving slower consistently can yield some really nice mpg numbers.
If you're going to read any of the links I've posted read this one (http://www.cleanmpg.com/forums/showthread.php?t=1224&highlight=pulse+glide). Go down the page to the Pulse and Glide sequence in the real world, and check out what the driver is doing. He'll accelerate (pulse) up to about ~35mph, maximum of ~40mph, and glide back down to ~30mph, wash, rinse and repeat. The point of this is that the car ends up optimizing engine efficiency by breaking up driving into an acceleration phase (minimize pumping losses) and coasting phase (engine off). This allows the driver to average ~35mph, but get much better mileage, something like 80-100mpg. If you compare the mpg the prius gets at ~50mph (the average speed on the epa highway test) which is ~50mpg, to the mpg the prius gets by averaging ~35mph which is ~80-100mpg. It's around twice the mileage, but the speed has only dropped by ~15mph. Guess what, the difference in the speed squared (50^2/35^2)=2.04 is just about two, meaning that by optimizing engine efficiency they can take advantage of the difference in energy required to travel at the two different speeds. Of course, rolling/sliding resisitance is still there, and plays a factor, as well as weather, but all in all I though this was a really good example of the increase in energy required to go faster.