Whilst we like to think of cycling as being a zero-emission activity, this isn’t strictly true.
Day to day the act of cycling will produce only the CO2 you breathe out during respiration and, without wishing to lower the tone, the methane that comes out of the other end. Unfortunately, the bike you are riding didn’t just appear out of thin air, it had to be manufactured and shipped to your local bike shop.
Parts are often made in different parts of the world and shipped to where they are assembled and boxed up.
Thankfully, even when the complete life cycle is taken into account, it still blows other forms of transport out of the water.
When the complete life cycle of each mode is calculated, here’s how they stack up (results in grams of CO2 per passenger per kilometer traveled):
- Bicycle: 21 g
- Electric-assist bicycle: 22 g (e-bikes scored well due to larger range of standard bicycle and therefore greater chance to replace passenger car trips)
- Passenger car: 271 g (based on short trips similar to those a bicycle could make)
- Bus: 101 g
The study was focused on the European Unions emission reduction goals, but the findings are useful for anyone in the transportation realm who needs data to back up arguments about CO2 emissions.
Source: New study compares bicycling’s CO2 emissions to other modes – BikePortland.org
However, there are some things we can do to keep our environmental impact to a minimum.
Choose your materials wisely
Whilst we’d all like to get around on something that wouldn’t look out of place in the pro peloton, the truth is that a high-end carbon bike is a bit of an environmental nightmare. Not only do they have a pretty short shelf-life thanks to carbon fibre being quite brittle, they use a lot of energy & water to produce and they’re very difficult to recycle.
Carbon fiber is neither biodegradable nor photodegradable. It’s a composite material, which means that it’s a combination of materials, whereby the different materials remain chemically separate and distinct within the finished structure. And as manufacturers have told us: it’s all about layers of material. The precisely engineered layers are what give a carbon frame superior performance, but those many layers also make it a bear to recycle
Source: The not so green bike: carbon fiber’s carbon footprint – BikeRadar
So, carbon is out and frankly, unless you are made of money, you are probably better off without it. That leaves us with the three metal frame types –aluminium, steel and titanium.
The trouble with metal, generally, is that it needs to be heated to ungodly temperatures in order to work with it. This requires a lot of energy, with aluminium producing slightly more CO2 per ton than steel by the end of the process.
Then there are the steel bikes, which are durable workhorses but also kinda heavy. On the plus side, they’re also very recyclable, and old steel can be endlessly recycled into new bikes (though good luck tracing the source of the steel on any particular bike). And in general, producing steel emits less carbon than producing aluminum — 1.8 tons of CO2 per ton of steel to 2.2 tons of CO2 per ton of aluminum — though I couldn’t find a bike-to-bike analysis for those two.
Source: What is the greenest type of bike frame? | Grist
Titanium also has very particular needs during manufacture, but whilst all three metal frame types are very recyclable, titanium frames are generally ones that’ll last you a lifetime; steel slightly less than a lifetime. However, both will be around long enough to earn their keep!
So, you’re in the market for a new bike –what do you go for?
Each frame material has its own characteristics and have rightly or wrongly earned a reputation for them. Carbon is well-known for the way it will smooth out the imperfections in the road; aluminium has a reputation for being harsh. Some may argue that Carbon smooths the road a little too much, with aluminium providing a more direct feel. However, tube sizes and geometries differ from frame to frame, so I’d be wary of generalising.
If money is an issue, you would arguably be better off with a good aluminium frame over a cheap carbon frame. You’d only have to have one bad fall and your carbon frame could be needing an expensive repair. Whilst aluminium is by no means indestructible (actually, it’s also quite brittle), it’ll stand a good chance of surviving a few more scrapes and dings. It’s also very recyclable.
If money is no object then your choice of frame really depends on what you plan to do with it. If you plan to race and have the support of a team, carbon is likely to be your main choice. However, if you don’t plan to race, you can consider steel or titanium. Steel frames have come on a long way with the likes of Genesis and Mason making some excellent steel bikes. They’re not that much heavier than a similar bike made from aluminium and will likely be just under the 10Kg mark.
If you plan to commute, tour or take part in Audax rides, steel would be a great option. It’ll last you for decades, it’ll look good in 20 years time and will give you a great ride, smoothing out a lot of the road chatter you can get on some aluminium frames. Plus, like aluminium it is also very easy to recycle, should you ever have to.
Titanium is often seen as the Holy Grail for tourers with cash burning a hole in their pocket. It’s the sort of frame that’ll last you a lifetime, is durable, light compared to steel but, rather like a Leica camera, it’s reassuringly expensive yet a little unnecessary.
The fifth option
Of course, the best way to help the environment, if you need a new bike, is to re-home a used bike. Cardiff Cycle Workshop take in unwanted bicycles, lovingly refurbish them and sell them on during set events between 1pm and 5pm each Friday.
Their range obviously varies depending on what has been donated to them, but they typically start at £60 for an adult bike and £10 for a child’s bike.
At the end of the day, it doesn’t really matter what you ride, just so long as you do!
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