Bicycles are truly beautiful machines. They are the most energy efficient form of transportation. You can travel pretty long distances with not that many calories.
Modern fat bikes will be more efficient than walking in the scrub desert where I live, in grasslands, in not too dense woodlands, on any kind of open dirt/sand.
I've done 100 mile MTB races, and while it's not as efficient as riding a flat smooth road on a road bike, it's probably still more efficient than walking.
Obviously at some point there's a line, where you can't ride a bike, but for most roads and trails, the bike is going to win.
I think that the comment I was responding to was about scenarios where are no human-created pathways, trails or roads. As I mentioned in some of these, modern fat (tire) bikes are still great; in others, it is true that walking would be the best choice (unless you're at the level of, say, Danny MacAskill).
But yeah, in some natural environments, with some kinds of bikes, you can beat walking. The Burning Man festival is a great example, but it is also a terrible place to live.
That's why in most cases, without smooth roads, bikes are not practical.
I think it's fair to point out that you should be referencing road bikes then when you say bikes are not practical. Advancements in tubeless technology, suspension, MTB groupsets with dinner plate low gears, derailleur clutches, and hubs/rims designed to take a beating while supporting wide tires can definitely make a bike more efficient than walking on most terrain.
- Fat bikes are more efficient than snowshoeing or breaking trail on XC skis.
- CX bikes are more efficient than walking in mud.
- Fatter tire gravel bikes are more efficient than hiking through sand.
- A bike with a 51T cog and 28T ring will be more efficient than hiking up steep grades until balance at low speed becomes an issue.
They don't require a flat and smooth surface, but do benefit from a road of some sort. How do you make a road? You ride on it over and over again. Ever seen a sheep track? Is that not natural?
A smooth and flat road, while not necessary, is better and does make things a lot more efficient. The same is true for any wheeled vehicle but cyclists appreciate it a lot more than motorists.
They are the pinnacle of personal transportation technology. Not aware of anything that comes close. I'm not sure how anyone can use a car, keep filling it with more and more fossil fuel and think "yeah, this is good technology".
Perhaps more carbon efficient, but 15x less energy efficient:
> Biking takes around 25 kcal/km [iii] above basal metabolism, which is equivalent to .11 MJ/km. A typical car in the US gets 25 mpg, or 9.5L/100 km, which is equivalent to 3.3 MJ/km. The Toyota Prius takes only 5 L/100km, or 1.7 MJ/km. So a typical car takes 30x more energy per kilometer than biking, and a Prius takes 15x more. This is what we expect given how much heavier cars are than bikes.
At equal diet, the bicycle always win. You don't eat significantly more meat because you are using a bicycle to move vs a total couch potato that would use a Prius and eat the same.
I disagree with this. On days I cycle 100km+ in a day I do eat vastly more than if I drive 100km and don't exercise.
The energy does have to come from somewhere. If you're only cycling 5km in a day the reason you don't notice the difference in food quantity is because the amount of energy used for that small amount of cycling does not really exceed the amount of energy your body uses in a day for everything else. When you're cycling 100km, it's a different story.
It's an interesting question, and in fact the conversion of food to mechanical energy isn't actually very carbon-efficient compared to electricity generation or even gasoline.
Cars are actually very efficient at what they do, it's just that what they do (hauling around a 1000kg metal box) is an inefficient way to transport a human, and that's where the inefficiency comes from.
If you fill up a large car with full occupancy and go on a long road trip, I'd venture to say it's carbon-wise likely to be more efficient than all of the occupants cycling, regardless of diet.
Part of the problem is that the former number is wildly variable depending on the type of food, the type of production and the amount of transportation to get it to where it is eaten.
Whereas oil-derived fuels are ... well, they vary but not as much. Certainly some food production models (e.g. alfalfa-raised cattle eating for meet thousands of miles from where they are raised) are truly horrible, and may indeed be worse than using fossil fuels.
That said, plant-centric, reasonably local food systems that don't use much in the way of synthetic fertilizer generate massively less carbon than any sort of oil production in terms of distance-travelled-per-unit-of-carbon.
Part of the problem is that people consider that the driver are some aliens that do not eat anything, or stay fit by just following a strict diet and without doing any exercise.
But the true reality is most people eat more, make reserves and a huge fraction of the population is either overweight or do physical activities in the purpose of burning those reserves and feel better. Mixing transportation with the later is quite efficient.
- 2000kcal from food = how much CO2 including all the energy needed to farm it?
If it's 2000kcal from beef, you're looking at about 72.88 kg [1]
If it's 2000kcal from fish, you're looking at about 15.21 kg [1]
If it's 2000kcal from brassicas, you're looking at about 6 kg [1]
- 35000kcal from gasoline emits how much CO2?
35000 kcal is 140440 kJ, which would consume about 4.36 liters of gasoline, which would be about 10 kg of CO2 emissions [2].
So the CO2 efficiency of a car isn't that much different, and falls somewhere in-between a biker on a fully meat and biker on a fully vegetable diet. Biking isn't vastly more efficient than a car, CO2-wise.
That said, a motorized bike is hellishly efficient, CO2-wise, and trumps almost everything else.
If you're going to do that, what about the CO2 (gasoline) emitted to collect the gasoline? Given you need oil to extract oil, it's still far, far, far less efficient.
It's miniscule compared to burning the gas, or the oil industry wouldn't exist, considering a lot of the oil extraction and refinement industry is powered by oil itself.
You could have also Googled that number instead of trying to make a comeback for the sake of it.
I used to be an elite racing cyclist, I know what it is to need fuel in a 200km bike race
Besides, riding at conversational slower pace only need a fraction of that energy. When I was commuting 75km a day myy food intake may be at worst marginally higher than a day off.
Correct, I wasn't trying to make a statement about specific diets, just that diet does make a huge difference in evaluating the carbon efficiency of cycling.
Not even close to true. I can ride 60-70 miles on reasonably hilly terrain on about 2000kcal. There’s no car that can come close to that. And that’s assuming drivers don’t eat (the McDonald’s wrappers I see by the side of the road proves that they do).
2000 kcal worth of food takes somewhere in the range of 6 kg (for vegetables) to 72 kg (for beef) of CO2 emissions to farm.
If you assume a gas car needs 35000 kcal to make the same journey it's about 10 kg of CO2 emissions.
You're making a kcal-to-kcal comparison, which is apples-to-oranges in terms of climate change. Climate change doesn't care about kcal, it's greenhouse gases like CO2 that do matter.
I know internet forum people are going to come back with a retort about how drivers also eat, but the fact is that cyclists do need to eat more than drivers to make the same journey, and the math puts the answer somewhere in the middle, you need to do the interpolation.
Your numbers are absolute nonsense. You excluded the CO2 to extract the oil and refine it into petrol/diesel. Nobody eats 2000kcal of beef: that's 6 whole burgers!
On top of that, your numbers assume that drivers don't eat, which is self-evidently not true!
This is miniscule compared to the amount emitted by burning it. It sort of has to be, or the industry wouldn't exist.
Congratulations, you're now deliberately fishing at the opposite and and nitpicking at the opposite end just to argue, at this point, when you could be looking at the entire pond.
Of course nobody eats 2000kcal of beef, I never said that. I was providing an extremum of all-brassica and all-beef so that you can interpolate somewhere between them, but evidently you're more interested in taking the endpoints and call it nonsense instead of doing the interpolation.
So go ahead and assume drivers eat. Bikers eat more. Again, do the interpolation. You get some data, you do the math, then argue. You will still find that it's within the same order of magnitude. CO2 from food production is a thing, and it's hugely variable depending on diet, that's the point.
> So go ahead and assume drivers eat. Bikers eat more.
Not that much more, and you're being disgustingly disingenuous by just grabbing the mid-point. To get 2000kcal, you're going to be eating more rice, potatoes and raw sugar i.e. carb-dense foods to fuel the ride. That's more like 2kg of CO2, so vastly below the 10kg of CO2.
I can safely exclude the beef, pork, etc. because that's food I'd eat "outside" of fuelling the ride. To spell it out for you: I won't eat more meat because I rode 65 miles, I'd eat more potatoes and cane sugar. Thus, that's what we measure in terms of excess CO2 produced vs just sitting on my couch.
Also, I'm being very generous to cars here. Most don't come close to achieving 65mpg, and certainly not on the route I measured with the steep climbs it involves.
