Well I just blasted past all you guys in my Sinclair C5. Eat my DUST!
[quote=“Ducked”]I think its probably not reasonable to entirely neglect metabolic increases due to cycling on the assumption that they will come from the existing, unmodified diet, though this may sometimes be true.
[/quote]
I think it is reasonable. The average diet contains far more calories than the average person needs for daily energy needs. We also produce far more food than we need. If we walked and cycled more for transportation we would not see a significant (if any) increase in food production and hence no increase in energy consumption. Don;t forget that a lot of people come home from a job they drove to and then go for a jog or bike ride. Those potential transport calories are already there. As for efficiency our bodies use even less energy when we do an activity often. Bike to work every day and pretty soon you are using very little energy to accomplish that task. That is obviously not the case for a car, which uses the same amount of energy no matter how many times it has driven a route.
Look, if you can convince me that a city such as Beijing, which 30 years ago had only cyclists and walkers is now experiencing a net decrease in energy use per capita because so many people have switched to cars and scooters, then you will have made a point. But good luck with that. 
I thought the same until I started following this up. The figures are out there to work out for yourself.
dieoff.org/page40.htm[/quote]
dieoff.org? That is not a scholarly source and the page you link to mentions nothing about cycling. Do you have any peer reviewed science to support your claim?
[quote=“Mucha Man”][quote=“Ducked”]I think its probably not reasonable to entirely neglect metabolic increases due to cycling on the assumption that they will come from the existing, unmodified diet, though this may sometimes be true.
[/quote]
Look, if you can convince me that a city such as Beijing, which 30 years ago had only cyclists and walkers is now experiencing a net decrease in energy use per capita because so many people have switched to cars and scooters, then you will have made a point. But good luck with that. [/quote]
Jeez! How many times? I’m arguing AGAINST Mr S, so this should be directed at him, not me.
But its not appropriate, when trying to analyse this kind of thing, to make assumptions which massively favor your intuitively preferred position, so I didn’t. I made conservative, worst-case assumptions, and, since the result still apparently tends to favor cycling, that tends to strengthen the case for cycling.
[quote=“Ducked”][quote=“Muzha Man”][quote=“Ducked”]I think its probably not reasonable to entirely neglect metabolic increases due to cycling on the assumption that they will come from the existing, unmodified diet, though this may sometimes be true.
[/quote]
Look, if you can convince me that a city such as Beijing, which 30 years ago had only cyclists and walkers is now experiencing a net decrease in energy use per capita because so many people have switched to cars and scooters, then you will have made a point. But good luck with that. 
[/quote]
Jeez! How many times? I’m arguing AGAINST Mr S, so this should be directed at him, not me.[/quote]
Duly noted. 
You seem confused about what a counter argument looks like. I have looked at the studies, and there are many, and cycling either comes out slightly below or slightly above cars in energy use. But not a single study I found takes into account how the human body works. If we plan on a 50km ride we don’t stop at Safeway and fuel up first. We may take a few snacks with us but this is not the same as using gasoline. In the first place, we have to eat and we regularly consume more calories than we need (this is not in debate though I can certainly supply you with some studies if you really need it). We also need to grow far more food than we eat as a hedge against crop loss. Finally our bodies adapt to exercise and use less and less energy the more we do an activity.
All combined, this argues (not assumes) that cycling will use far less energy per km than the typical study is showing because most of the energy used will be “free” or already accounted for.
http://centres.exeter.ac.uk/cee/coley/walking.pdf
I don’t have time to dig further into this, but I’m pretty sure the above figures do not calculate the carbon cost of manufacturing, however significant that may be. Anyway, I’m off for a bike ride along the river. If you notice a disgusting yellow haze over the city today do not blame me for it.
And we have a winner!
You seem confused about what a cart looks like, relative to a horse.
I was attempting an (admittedly crude) analysis, not an argument. The argument should really come after.
If one wanted to go straight to an argument, yours is quite a good one, but it involves an assumption that suggests bias, and which could be challenged.
Well, thanks. (If that’s a retraction/acknowledgment)
If it isn’t, Sigh!
[Edit: This is not intended as a dig at AntarcticBeach. Nothing wrong with his posting, though I imagine counter-postings might be possible. Indeed, if Mr Man’s above impression of published research “there are many, and cycling either comes out slightly below or slightly above cars in energy use” is accurate, many counter-postings would be possible.]
I spend [strike]much[/strike] some of my paid working time telling students that undigested cut-and-pasting of conclusions is not research, analysis, truth or victory, and that logical consistency is key.
Here we go again.
If you check back above, you’ll see that both you and Mr Man rejected the emissions factor approach.
Mr Man’s position was that no extra food was consumed as a result of cycling. Your position was less clear, but seemed to be similar.
This paper takes the emission factor approach. It attempts to account for the production-energy embodied in the British diet, and finds the calories consumed by cycling to be a lot less emissive than walking or driving. I’ve got no problem with that. I got a smaller difference, but that was a crude back-of-the envelope job based on US numbers.
You pair would have a problem with it, however, if you cared about logical consistency.
Mr Man’s objection is key to the validity of this approach, and the paper seems to body-swerve it a bit, though perhaps unintentionally.
“Recent work (Westerterp, 2001) has re-enforced the message that moderate levels of activity, such as that represented by walking and cycling, do increase annual energy expenditure”…“This observation suggests the estimation of implied emission factors for various activities”
Note that it does not actually state calorific intake is increased, (though its probably implied/assumed) so Mr Man’s objection is not directly addressed.
[quote=“antarcticbeech”]
I don’t have time to dig further into this, but I’m pretty sure the above figures do not calculate the carbon cost of manufacturing, however significant that may be. Anyway, I’m off for a bike ride along the river. If you notice a disgusting yellow haze over the city today do not blame me for it.[/quote]
Do you mean the relative cost of food manufacture and transport compared with the cost for oil extraction and transport? They don’t seem to do that, though I don’t know what the E(food)/E(diet) refers to.
[quote=“greenmark”][quote=“antarcticbeech”]
I don’t have time to dig further into this, but I’m pretty sure the above figures do not calculate the carbon cost of manufacturing, however significant that may be. Anyway, I’m off for a bike ride along the river. If you notice a disgusting yellow haze over the city today do not blame me for it.[/quote]
Do you mean the relative cost of food manufacture and transport compared with the cost for oil extraction and transport? They don’t seem to do that, though I don’t know what the E(food)/E(diet) refers to.[/quote]
Its apparently the production energy for the food(excluding calorific content)/calorific content, so its about the energy cost of producing the food.
He takes an IPCC published figure for the cars carbon emission, which I assume accounts for the full energy cost of the fuel, but might not account for the full lifetime carbon cost of running and producing the car, which may be what A. Beech meant.
That was from Scientific Murkin? 
Jet planes are incredibly inefficient and get more inefficient the faster they go. It’s been said that the amount of fuel used on a fully laden long-haul flight – say from New York to LA on a 747 – is approximately the same amount that would be used if every passenger climbed into their own personal gas-guzzling SUV and drove across the US.
Yeh, might have remembered that wrong. It was probably about 40 years ago.
[quote=“greenmark”][quote=“antarcticbeech”]
I don’t have time to dig further into this, but I’m pretty sure the above figures do not calculate the carbon cost of manufacturing, however significant that may be. Anyway, I’m off for a bike ride along the river. If you notice a disgusting yellow haze over the city today do not blame me for it.[/quote]
Do you mean the relative cost of food manufacture and transport compared with the cost for oil extraction and transport?[/quote]
I meant simply the carbon cost of manufacturing a car and the carbon cost of manufacturing a bicycle. Anyway, I did a little more reading and found this, which relates to what you stated:
http://www.carbonunity.com/sites/default/files/camden_lca_report_final_10_03_2006.pdf
And I also found this abstract (only the abstract is freely available) :
http://ivem.eldoc.ub.rug.nl/FILES/ivempubs/publart/2002/TranspResDBouwman/2002TranspResDBouwman.pdf
one thing that people may also be neglecting to consider is that burning food is carbon neutral (like burning wood) while burning petrol is definitely not.
stick that in your equation and smoke it.
Yes and there are a number of studies showing the health benefits of walking or cycling to work, and others showing the detrimental effects of vehicular air pollution.
I’m sure that ‘big oil’ and ‘big car manufacturing’ have the ability to fund significant disinformation on the internet, but there is nothing in the scholarly literature about cars being more energy efficient than bicycles. I may be wrong - I doubt it - but, if so, I’m all ears.
antarcticbeech
And bicycles are certainly lot more fuel efficient: they burn no fuel at all. Mine doesn’t even have a petrol tank.
[quote=“urodacus”]one thing that people may also be neglecting to consider is that burning food is carbon neutral (like burning wood) while burning petrol is definitely not.
stick that in your equation and smoke it.[/quote]
Shan’t.
This whole discussion is predicated on the FACT that western agribusiness (and particularly US)food production is carbon intensive, and its the (mostly fossil fuel) energy inputs required to produce the food that is under consideration. The paper antarcticbeech cites above specifically excludes the energy content of the food from its calculation. My half-assed calculations took a figure for the oil required to feed an American to calculate the oil-equivalence of the calories burned, and any relevant papers cited in this context will take a similar approach.
The carbon-neutrality of photosynthesis, though of course a matter of fact, is irrelevent in this context, and has been from page one.
Ach! Away and temp yersel, laddie.
I do take your point on the carbon-neutrality of food. Of course the argument is about total oil costs involved in making the food (as well as making and transporting the cars, bikes, etc).
There is a hell of a lot less steel in one bicycle than in one door of a car, so that’s a fairly easy win by the bicycle on that score. And I have bicycles that are 30 years old and still going strong. Well, i have four of them, so maybe that’s a bit skewed by the fact I collect classic bikes.