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"Riding a bike vs driving actually causes more pollution (because farms make lots of pollution) [unless you replace exercise you anyway do with bike riding]."

"Riding a bike vs driving actually causes more pollution (because farms make lots of pollution) [unless you replace exercise you anyway do with bike riding]." That is totally nonsense. You simply invented that nonsense. Let's put some numbers in : My bike weights 15kg, my body 85. So I move around 100kg with my bike. My small Toyota weights naked 1500kg, so I am moving 1700kg around(including my weight and gas or fuel as we call it). 1700/100 = 17 times more weight. I move around at 30km/h max speed with my bike, normally around 15 or so. With my car it is over 80km/h. The resistance f the air is proportional to the square of the velocity so we are using over 28 times more energy per kg(as velocity resistance surpasses rolling resistance by far). So that's it :28x17 = 476 times more energy So let's consider half of that because velocity resistance is going to be similar to rolling resistance somewhere in the middle, that's over 200 times more energy, but then you have to add the car shape that exposes way more than 5 times my surface on the bike to wind. Farms don't make lots of pollution, and their pollution is natural, My grandpas had a farm. Dung is not the same kind of pollution than mercury or exotic organic compounds in the car's paint, or in the car's polymers, or in diesel exhaust.

ars 13y ago
Lots of numbers and you ignored the only two important ones because it doesn't fit with your preconceived notion. 1: The efficiency of converting that energy into motion. A car is MUCH MUCH more efficient than a person. 2: The amount of energy from diesel needed to grow those food calories in the first place. Again, a car comes out way way ahead. > Farms don't make lots of pollution, and their pollution is natural, My grandpas had a farm .... not the same kind of pollution .... in diesel exhaust. A farm with no tractor. Interesting. Maybe in your grandpas day, but certainly not today. Farms use a TON of diesel to grow that food.
- phaemon 13y ago
  If both of those were correct, it would cost more to cycle 10 miles every day than it would cost to drive 10 miles every day. It doesn't, therefore your points are wrong.
  - ars 13y ago
    Except it does actually cost more to cycle. You just don't notice because when you buy food it doesn't have a label saying where you used those calories. It does depend on what you choose to eat though. If you eat beans vs burgers. The cheap food comes close enough to driving to not matter, but most people eat nicer food and then it's more expensive to bicycle.
    - walshemj 13y ago
      No it doesn't I used to cycle over 16 miles day and I did not eat any more food - I just lost weight which made me healthier.
    - rzt 13y ago
      I'm sorry, but this is crazy science. Looking at kilojoules and efficiency of energy, a bicycle is much more efficient on the order of hundreds, just looking at mechanical resistance and the energy needed to get the vehicle moving. Also, while competitive/fast cycling requires large amounts of food to sustain, the extra fuel needed to commute by bike doesn't require much more than an extra handful of almonds or in my case, an extra beer in the evening. The human body gets more efficient at a given exercise over time –– that's why calories-in/calories-out is never an equal proposition in a trained athlete (and regular bike commuting is in some ways "training.") If you break it down into prices, bike commuting might cost an extra $1-$2 in food per day. OK, fine. However, that mitigates the $3-4 in fuel cost for mileage over a 20 mile commute. Maintenance costs on a bike are negligible compared to a car: $100 in chains, cassettes and brake pads annually vs. the $1,000-2,000 in usual car maintenance costs per year (PLUS, repairs). As for environmental costs: yes a bike requires carbon to build and transport across the Pacific. But the heavy huffing-and-puffing C02 contributions of a cyclist is negligible to that of a car.
    - phaemon 13y ago
      > Except it does actually cost more to cycle. No, this is plainly wrong. Don't take my word for it, work out the cost per mile for yourself. You'll quickly see that you have to choose ridiculously low car costs vs expensive, low calorie foods to get it remotely close. With average car prices vs cheap food...it isn't even a contest.
- sophacles 13y ago
  Lets look at a model. You are making the claim, so you provide the cited numbers to fill it in. To begin with - lets assume all joules are equally polluting. This isn't true, but we'll get to that. Jp = the number of joules needed to move a person a distance. Je = the number of joules needed to deliver Jp to the point of use. Jt = the total number of joules for a mode of transport Simply: Jt = Jp + Je Therefore a first approximation is to compare Jt(bike) with Jt(car) However there are other factors that must be accounted for in this equation: Jm - the total number of joules needed to manufacture the transport (full supply chain), and deliver it to first point of use. Jl - the number of joules needed by a person anyway - farming can't just be eliminated, people require food to remain people. (Jl stands for joule's life) Jl' - the number of joules needed to transport the minimal "keep people living" joules to point of use. It should be noted, that Je and Jl' are related in the bike case, so Je in the bike case will only be the extra energy required to deliver additional food, not the energy required if the Je for a bike were delivered in an entirely separate manner. With Je for a car - the energy source, energy delivery etc are an entirely different infrastructure. So factoring those in we get: Jt = Jp + Je + Jm + Jl + Jl' Of course - at the beginning I mentioned not all joules are created equal. So we need some sort of pollution index. I don't know a simple polution index formula, but assuming it exists, we will call it P. The output will be a normalized value that can be simply added to understand total polution. So: P(Jt)= P(Jp) + P(Je) + P(Jm) + P(Jl) + P(Jl') I want to note about the pollution function - the pollution of P(Jp) is essentially 0 in the bike case, because it is just metabolism. P(Jl) will most always be close 0, because it is metabolism again. The polution from delivery is captured in other variables. This model could be further refined into pollution per travelled km, rather than the pollution per joule used. It could be better refined by including the Jm costs as an amortization of efficiency over the total number of travelled km. Etc. But for now, the model as stands is a good way of determining the claims first order validity.

ars 13y ago

Lots of numbers and you ignored the only two important ones because it doesn't fit with your preconceived notion. 1: The efficiency of converting that energy into motion. A car is MUCH MUCH more efficient than a person. 2: The amount of energy from diesel needed to grow those food calories in the first place. Again, a car comes out way way ahead. > Farms don't make lots of pollution, and their pollution is natural, My grandpas had a farm .... not the same kind of pollution .... in diesel exhaust. A farm with no tractor. Interesting. Maybe in your grandpas day, but certainly not today. Farms use a TON of diesel to grow that food.

phaemon 13y ago
If both of those were correct, it would cost more to cycle 10 miles every day than it would cost to drive 10 miles every day. It doesn't, therefore your points are wrong.
- ars 13y ago
  Except it does actually cost more to cycle. You just don't notice because when you buy food it doesn't have a label saying where you used those calories. It does depend on what you choose to eat though. If you eat beans vs burgers. The cheap food comes close enough to driving to not matter, but most people eat nicer food and then it's more expensive to bicycle.
  - walshemj 13y ago
    No it doesn't I used to cycle over 16 miles day and I did not eat any more food - I just lost weight which made me healthier.
  - rzt 13y ago
    I'm sorry, but this is crazy science. Looking at kilojoules and efficiency of energy, a bicycle is much more efficient on the order of hundreds, just looking at mechanical resistance and the energy needed to get the vehicle moving. Also, while competitive/fast cycling requires large amounts of food to sustain, the extra fuel needed to commute by bike doesn't require much more than an extra handful of almonds or in my case, an extra beer in the evening. The human body gets more efficient at a given exercise over time –– that's why calories-in/calories-out is never an equal proposition in a trained athlete (and regular bike commuting is in some ways "training.") If you break it down into prices, bike commuting might cost an extra $1-$2 in food per day. OK, fine. However, that mitigates the $3-4 in fuel cost for mileage over a 20 mile commute. Maintenance costs on a bike are negligible compared to a car: $100 in chains, cassettes and brake pads annually vs. the $1,000-2,000 in usual car maintenance costs per year (PLUS, repairs). As for environmental costs: yes a bike requires carbon to build and transport across the Pacific. But the heavy huffing-and-puffing C02 contributions of a cyclist is negligible to that of a car.
  - phaemon 13y ago
    > Except it does actually cost more to cycle. No, this is plainly wrong. Don't take my word for it, work out the cost per mile for yourself. You'll quickly see that you have to choose ridiculously low car costs vs expensive, low calorie foods to get it remotely close. With average car prices vs cheap food...it isn't even a contest.
sophacles 13y ago
Lets look at a model. You are making the claim, so you provide the cited numbers to fill it in. To begin with - lets assume all joules are equally polluting. This isn't true, but we'll get to that. Jp = the number of joules needed to move a person a distance. Je = the number of joules needed to deliver Jp to the point of use. Jt = the total number of joules for a mode of transport Simply: Jt = Jp + Je Therefore a first approximation is to compare Jt(bike) with Jt(car) However there are other factors that must be accounted for in this equation: Jm - the total number of joules needed to manufacture the transport (full supply chain), and deliver it to first point of use. Jl - the number of joules needed by a person anyway - farming can't just be eliminated, people require food to remain people. (Jl stands for joule's life) Jl' - the number of joules needed to transport the minimal "keep people living" joules to point of use. It should be noted, that Je and Jl' are related in the bike case, so Je in the bike case will only be the extra energy required to deliver additional food, not the energy required if the Je for a bike were delivered in an entirely separate manner. With Je for a car - the energy source, energy delivery etc are an entirely different infrastructure. So factoring those in we get: Jt = Jp + Je + Jm + Jl + Jl' Of course - at the beginning I mentioned not all joules are created equal. So we need some sort of pollution index. I don't know a simple polution index formula, but assuming it exists, we will call it P. The output will be a normalized value that can be simply added to understand total polution. So: P(Jt)= P(Jp) + P(Je) + P(Jm) + P(Jl) + P(Jl') I want to note about the pollution function - the pollution of P(Jp) is essentially 0 in the bike case, because it is just metabolism. P(Jl) will most always be close 0, because it is metabolism again. The polution from delivery is captured in other variables. This model could be further refined into pollution per travelled km, rather than the pollution per joule used. It could be better refined by including the Jm costs as an amortization of efficiency over the total number of travelled km. Etc. But for now, the model as stands is a good way of determining the claims first order validity.