If I ever had a training schedule, it's been entirely forgotten as the (previously) unwritten rule has become "if it's dry - ride!" It's difficult to know whether this type of low-discipline, varied riding is the most effective way of going about things, but I feel that any time on my real bike is worth far more than in the gym. I might test that hypothesis a bit more in the future.
Anyway, then. What I mostly wanted to write about today was a genuine look at the carbon impact of cycling, with genuine numbers. Not a "most people" sort of analysis, mind - this one's looking squarely at me. So here we go.
What set me wondering about this was an interesting article about the bicycle component manufacturer Hope (http://www.bikeradar.com/news/article/hope-technology-behind-the-scenes-30437). Since Hope machine most of their bits, there is a lot of resulting off-cuttage that must be sent back round the recycling loop, and I wondered how much this would affect the carbon footprint of the bike.
As it turns out, this part isn't as bad as I had feared. According to the Inventory of Carbon & Energy materials table, creation of virgin aluminium emits 12.79kg of CO2 equivalent per kg of aluminium, whereas recycling requires only 1.81kg CO2e/kg, so an order of magnitude reduction in energy required to recycle rather than extract aluminium. However, the overall number is still large: this is a far cry from the 2.89/0.47 of steel, and not all that much better than the 20.6-42.5/14.7 of titanium.
Let's say, for simplicity's sake, that my bike is 10kg, and consists primarily of aluminium, and, as a worst-case scenario, the average number of times that the aluminium has had to go around the cycle is 3 (i.e. virgin, then 3 recycles) to account for machining. This means that that material cost of my bike is 182kg of CO2e. A pretty big number, but only the same as emitted from burning 80 litres of petrol. Two tanks, and you've paid for your bike. I'll be conservative and say 400kg all in for manufacturing and transport, and then amortise that over the projected life of the bike - again, I'll be conservative, and say 10000 miles.
So, at a guess, for my road bike, I've got an embodied carbon footprint of around 40g per mile, or 25g per kilometre. Compare this to the 130g+ of the average family car on the market today, and we're already looking pretty good - especially considering that the full lifecycle emissions of the car have been ignored.
What about my fuel, then?
For better or worse, I mostly feed myself bread, getting through over 1000 calories a day of the brown stuff. This is my main cycling fuel, along with pasta and rice.
- Assuming 1000 calories per hour, at 20mph (i.e. 50 calories/mile),
- and a calorific content of bread of 2600 calories/kg (http://www.alfitness.com.au/food-calorie-counter.asp?id=443&foodName=Bread&page=),
- emitting 0.75kg CO2e/kg bread (http://timeforchange.org/eat-less-meat-co2-emission-of-food)
that comes out to 19.2g of bread per mile, and 14.4g of CO2e. Per kilometre, then, that drops to 9g.
So, here we are then. A total of 34g of CO2e/km. Not a bad ratio, for a single person. As soon as you double it there might be issues with the 60g/km target that vehicles may one-day hit, and with 4 of you, you're getting into the region of currently achievable emissions figures (again, we're ignoring embodied costs in the car, somewhat unfairly).
So, there's what I consider to be a realistic figure. It's noticeable, though, just how much it is dominated by the embodied carbon in the bike. Merely by switching to steel, you can downgrade that a good 5 times, and, of course, how you fuel yourself can make a significant difference.
Carbon fibre? Well, I just don't know about carbon fibre.
Now I'm starting to wonder what happens when we include the embodied carbon in the road infrastructure.
Good trails!
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