BIKEPGH MESSAGE BOARD ARCHIVE

While I realize that the carbon footprint of a bike isn't completely neutral, I don't believe that it's anywhere near 1/10 of that for a car.

My first thought is that that 1/10 of 1% would be high.

I looked at one of the papers authored by Shreya Dave. He makes attempts to formulate standards of Life Cycle Analysis for bikes and compare it to standard estimates for cars, but I'm thinking he makes a few assumptions that lead to a really high manufacturing and infrastructure cost for bikes. Assuming bike trail costs are proportions to car road costs when normalized for vehicle WIDTH, rather than weight. Mentioning, but then not calculating in, that short trip emissions for cars are about 40% higher due to start up costs, but not factoring that in the calculations (almost all bike trips substituting for a car trip would be "short trips" in car terms, yes?) There would be further "short trip " costs in manufacturing for cars, too - the wear cost per mile for short car trips is way higher than for highway travel.

Still the article changes some views I have. Even with the stuff I mentioned, the bike probably has a per mile footprint that is 2% to 6% of the footprint of a car.

Shockingly high for bike.

I read the article but not the papers.

I saw that "A huge portion of that difference came from fuel combustion". But it wasn't clear if the carbon footprint of making the fuel & getting it to the pumping station was part of the calculations.

Well, what we seem to have have here is an unpublished white paper written by an MIT Masters student. Whose advisor appears to have been let go, or has otherwise decided to move on. This would be be much more interesting had it appeared in a peer-reviewed journal or conference. I really don't know anything about this field, but I would feel more comfortable if some knowledgeable practitioners had passed on the validity of this study.

More subjectively:

Do you sincerely believe that the consequence of walking or cycling to work has a impact comparable to taking the bus or driving your car? Is an order of magnitude difference just in the noise? Is the impact of replacing the brakepads on your bike the same as replacing the brakepads on your car?

And, shouldn't we factor in the health care costs due to lack of exercise? (I understand that, e.g., diabetes is expensive to treat.)

get a used bike, let someone else do all the dirty work

@Mick, I agree this article is shocking. First off the 10% sedan argument. Secondly, the 20-times claim for an off-peak bus. SERIOUSLY? How does a bicycle come anywhere NEAR the cost of an off-peak bus????

How far do I need to ride my bike to pay back the carbon footprint of spending so much time on the internet?

I think Ahlir hit the money. There are sErIoUs reasons this isn't in a peer- reviewed paper.

Still, it's easy for the costs of biking to outstrip what one might think.

I ran into this before with "life-course-purchase-price" estimates.

I'm unlikely to ride a bike much more than 10K miles, but a car will go 200K, easily. So purchase price per mile is similar between cars and mid-upper priced bikes.

How the f**k can that happen with a 22 lb bike versus a 4000 lb motor vehicle with enclosed seats, carpet, a stereo, and convenient little warning lights to let you know gas is low and a door is open?

Boggling.

whenever one makes cost of life calculations, one must draw the line somewhere, and it's inevitably in a location that one camp or the other will disagree with because of what was included or discluded.

Mick - I can think of two reasons the purchase price comparison doesn't favor bicycles: volume, and irresponsible waste disposal/manufacturing procedures. If vehicle manufacturers had to charge customers the true cost of responsibly manufacturing a single car, including living wages for all workers involved at every tier and responsible waste disposal (including power generation) at every tier, the comparison would look different. Even if bicycle manufacturers were comparably restricted, I think those two factors would tip the scales back in the cycling direction.

Yes, I know car manufacturing is much cleaner than the average hippy like me thinks it is, I worked in the industry.

I'm not sure comparisons do much anyway other than make people feel good about their choices. An important thing, but still. Is it ever a deciding factor?

Mick, the problem isn’t in the calculation, but in the indicator. Dollars per mile is one indicator, dollars per year is another – and the bike wins the second one hands down.

How about ‘enjoyable’ miles per trip? Bike wins again unless you own a 60’s era British ragtop. How about injuries per mile? Probably favors cars. Infrastructure cost per mile? Bikes win. Adams apples per commute? Cars win.

So what should be the gold standard for comparisons?

Some enterprising young engineering TA once said to me "success is always achievable - just define your metric carefully".