What Material Makes a More Sustainable Bike?
When I first got into biking I found it hard to choose the right material. Aluminium was cheap and plentiful, titanium was expensive and shiny. Carbon fiber just confused me. Eventually I got to learn the differences between them all, but I know I wasn’t the only one who had these problems. There are people out there now who are looking at a list of bikes wondering what the difference is.
Then I started to get onboard with Route Assembly. I started looking at the differences in material from a whole new angle. Eco-friendliness. If we wanted to make the industry better we needed to look at our materials and make sure they’re as eco-friendly as possible. Now I’m not the expert in this here, but I wanted to give a quick overview of some common materials for people coming into the industry.
Aluminium is one of the most common kinds of material for production bikes. It’s lightweight, durable and inexpensive. However it is stiffer than most other materials which means its shock absorption leaves something to be desired. With its lower shock resistance aluminium doesn’t work as well as some other materials for off road bikes, it just isn’t as durable as something like titanium. So chances are it’s going to need replacing a lot sooner. Don’t get me wrong an aluminium mountain bike will do what it needs to. It might even be very good, but higher end mountain bikes will often be made of stronger stuff.
For bikes that are generally lower impact, aluminium is a great material. Road bikes and cargo bikes designed to be used in an urban setting don’t take the same kind of beating. Aluminium frames are fairly inexpensive to produce and don’t carry a price tag that will scare away new riders. It strikes a nice balance between performance and cost effectiveness. There is one property of aluminium that makes it really interesting from an eco-friendly standpoint too.
Needing to be replaced more often means high production numbers. More bikes, more emissions. That offers a barrier to sustainability but there’s a few saving graces. Aluminium is infinitely recyclable, it doesn’t lose any material properties as it’s recycled. In fact nearly 75% of all of the aluminium that has been produced is still in use. Even better? It only takes 5% of the energy required to produce fresh aluminium to recycle it and, it has a huge financial saving too. Even when taking into account the costs of collection is taken into account. This makes aluminium a very green material to work with once it’s coming from recycled aluminium.
Just because aluminium can be recycled doesn’t mean it all is though. Once frames are sold they don’t necessarily come back. Plenty of companies have programs in place to facilitate this but it’s not a certainty it comes back to them at all.
Steel frames are on the heavier side, but it also tends to be more flexible. So unlike aluminium it has great shock absorption, it is a fantastic material for mountain bikes or any bike that’s going to take a lot of impact. It helps for a smoother ride on roads too, but honestly a steel frame is probably overkill for the average commuter.
Although it’s heavier, this isn’t always an issue a well made steel bike mitigates this with natural springiness, and a good set of wheels helps. Just because the weight isn’t too noticeable doesn’t mean a rider doesn’t have to overcome more inertia to get going. Or that it’s any lighter when they have to wheel it instead of riding it. It’s not as corrosion resistant as aluminium either. Steel can rust in the wrong conditions so it’s not a great material for all climates or for occasional riders.
When everything is considered steel is a great material for bikes but it’s higher weight and cost can put off a lot of riders. People who want a more durable frame without paying the cost of titanium will likely look to steel though. The type of steel matters too, carbon steel is generally speaking inferior to the more modern chromalloy. Chromalloy offers better strength to weight ratios and corrosive resistances to regular high carbon steel.
Like aluminium, steel is really easy to recycle. Most of the steel we use now has already been recycled. This means steel frames can turn into a circular model. However the steel industry also produces a massive amount of CO2, in fact steel production accounts for a bigger negative effect on the climate than any other industrial material manufacture. The truth is that while steel can be recycled easily it is still produced in large quantities.
Lighter and stronger than steel. Titanium produces some really impressive frames. It has the highest strength to weight ratio in frame materials. A titanium frame is likely to last for life and often comes with lifetime warranties. This means the carbon footprint of titanium bikes could be considered lower per customer since the number of bikes produced is much lower.
It’s renowned for its shock absorption too so it gives a seriously comfortable ride. It is also pricey. It’s doubtful most riders will spend the money on titanium unless they’re really serious about cycling. Honestly this is the only real barrier with titanium frames. They are expensive to purchase and if it does need to be repaired that could be expensive too. It’s hard to find, but that’s in part because of low demand.
There is a reason titanium frames are expensive, it’s the most expensive raw material we’ve listed here and creating a frame is labour intensive. So the cost of production is super high, add that to the decreased demand and it’s pretty clear to see why most companies don’t produce titanium. It’s a risk, high investment and less sales, for most companies it just makes more sense to stock aluminium, or even steel frames.
It is as recyclable as steel though. Without losing material to rust either since it has high corrosion resistance, but due to its durability it is also not likely for a bike to be recycled. In short you might be using recycled titanium in a bike but it’s probably not circular. Like aluminium, titanium doesn’t lose much quality when it’s recycled. But there isn’t much titanium recycled from products since they’re expected to last for so long.
This is one of the more confusing materials to people who are first getting into bikes. You keep seeing articles about how it is laterally stiff and vertically flexible. It is a great material though. It’s lightweight, durable, flexible where it needs to be.
It carries a big price tag to manufacture though. With the need to purchase moulds and a labour intensive process, making a CF frame can take a lot of time and money. They are also less recyclable than other materials. It’s possible to recycle but most of the carbon from bike frames becomes chopped carbon which goes on to be used in other products.
That being said the carbon cost per frame is generally lower than an aluminium frame. So it really depends on the way you are measuring the sustainability of the material.
Carbon frames are popular though. For competitive cyclists it cuts down on weight and makes it easier to ride for long periods of time. Nearly every Tour De France winner in the past twenty years has used a carbon bike. Technically CF frames are the stiffest of frames, which you might think means they don’t have much shock absorption, but check out some forums and you’ll see that people find CF frames really smooth rides. This is because the layout of the fibers means it can be stiff in one direction while flexible in another, so a rider gets a great balance between the two. A lot like titanium though CF frames come with a big price tag, usually.
The Future of Carbon Frames
Carbon frames are something to look out for in the future though. Advances in production methods- such as additive manufacturing- lower the production and carbon costs.
Recycling of CF is also advancing. Inline solvolysis is being used to separate carbon fibers from resin while keeping the same properties as virgin carbon fiber. While there were difficulties adding resin for reuse, it was found that this recycled carbon fiber worked for use in additive manufacturing.
So What Material Works?
Aluminium is 100% recyclable, but that only matters if you actively use recycled aluminium. Lower carbon emissions per bike produced make carbon fiber seem really green. But if your bike is just going to end up in a landfill once it’s broken then it’s not really sustainable. So it isn’t as simple as saying steel bikes are more environmentally friendly. The thing to take away from this isn’t that some of these materials are more sustainable than others. Rather all of these materials have the potential to be sustainable so long as they are responsibly sourced. Any company producing bikes should source their materials responsibly.
The truth is that no matter what material a manufacturer uses it’s important to make it as sustainable as possible. And it’s a lot more complicated than I have the space to cover in this post. Shipping distances, whether or not a facility uses green energy and plenty of other factors all matter. Carbon fibers might be generally less carbon costly than aluminium but if it’s being produced in a coal powered facility while the aluminium is produced in a solar powered one that could change. It’s important to look into where your material is coming from and make the best choice you can.