Originally Posted by
mschwett
strange article, which mixes seemingly authoritative facts, assumptions, and just silliness more or less completely out of context.
Somewhat agree. I find most any article that says bicycling is planet harming to be akin to the biblical references to motes and logs and eyes. Automobiles are around in greater numbers and have a far larger carbon footprint than bicycles ever will.
that a carbon frame has greater embodied carbon than a steel frame is very believable…. but the amounts referenced are almost meaningless assuming one is not buying (and throwing out) a new carbon bike every week. the highest stated estimate, which came not from a carbon frame maker or an independent study but from a steel frame maker (biased much?) shows the equivalent of around 30 gallons of gasoline consumption. not great, but hardly a reason to avoid an entire category of product which has other benefits.
While I agree, I did find the amount of carbon dioxide output for making virgin carbon fiber to be somewhat staggering. To make virgin steel from ore to finished product, roughly 5 tons of CO2 is produced per ton of steel. For aluminum, it’s 16 tons CO2/ton of aluminum. For carbon fiber, 29.5 tons of CO2 is produced for each ton of carbon fiber. That is a huge footprint! Less carbon fiber is made than steel and it takes less carbon fiber to equal steel but that’s still a large initial deficit.
Additionally, the amount of energy needed to recycle steel and aluminum drops significantly. For steel, recycling of the steel produces about 5 times less carbon dioxide…1.4 tons CO2/ton of steel. Recycling aluminum reduces the carbon even more dramatically…0.5 tons of CO2/ton of aluminum.
Carbon fiber is problematic since the fiber is difficult to recycle. Currently the fiber is pyrolized to recycle which requires a considerable amount of fuel to do. Recycled carbon fiber
does significantly reduce the carbon footprint but only to about 4.5 tons CO2/ton of recycled carbon fiber. That’s almost the same as virgin steel.
the life cycle emission chart per km is just ridiculous, is there even such a thing as a “carbon fiber cargo bicycle with electric motor?” never seen one. and the range of possible life spans for the calculation - 5,000km to 20,000km for an “aluminum bicycle” are absurd. I’ve ridden my road bikes 10,000km in one year, and would expect them to last 10 to 20 years at least, cutting the emissions per km by an order of magnitude, revealing just how trivial the carbon emitted in the production of the frame and other components are.
the author clearly has an agenda. I’m sure the clouds are cowering at his fists.
Yes, his estimates seem low for a lifetime of a bicycle. Although from my own records of bicycles…40 of them…I average only about 2600 miles per bike with a high of 22,000 lifetime miles and a low of 57 miles. Four of those bikes were disposed of because they broke (3) or were wrecked due to a car accident (1). Most of the rest passed out of my hands so I have no idea how long they lasted.
But, over all, the article has a bit too much self-flagellation to be taken seriously.