Carbon fibre offers advantages in terms of weight, stiffness and strength – attributes that have led to it being ever-present in bicycle frames and parts. But what happens when they near the end of their lifecycle? The overwhelming answer: join the growing piles of industrial waste. Despite the environmental concerns, the cycling industry continues to produce carbon fibre products en masse because of their high performance and consumer demand. The allure of carbon fibre’s performance characteristics and sleek aesthetic has become a driving force in modern cycling, especially at the professional level, where marginal gains in performance can make all the difference.
But it’s also energy-intensive to produce; up to 34 kg of CO2 are produced for every kilogram of carbon fibre, roughly double that of aluminum although the latter’s carbon intensity varies by country of production. With the Union Cycliste Internationale (UCI) estimating that 90% of end-of-life carbon fibre equipment ends up in landfills, this “wonder material” presents a serious sustainability challenge.
Recycling carbon fibre has become more achievable with new technologies and resources, and some bike brands have begun to tiptoe into creating both products that are recyclable and systems to put recycling into practice. Those approaches – like Hunt’s recently launched H_Cyclo wheels with recyclable resin technology – are a sign of a potential shift. But the cycling industry faces two main challenges – one internal and one external – in implementing it.
The biggest factor is outside the industry’s control: the technologies that determine carbon fibre’s recyclability are being developed by industries like aerospace and wind energy, at a scale far beyond the use of the material in bikes or even sporting goods as a whole. The bike industry has little real power to drive that innovation.
But beyond small projects like Hunt’s, the industry doesn’t seem that interested, either. Despite advancements in carbon fibre materials and manufacturing, many brands are still hesitant to leap into changing their methods. Even as some brands deride carbon as the “McDonald’s” of bike frame materials as one source put it – cheap, ubiquitous, and wasteful – it has become the dominant material for high-performance bicycles, wheels, and components, whether we like it or not.
Cycling’s relationship with – and reliance on – carbon is a complicated one, and even with the advent of new technologies and resources for recycling it, the industry is still far from achieving circularity when it comes to one of its most beloved materials.
The challenges of carbon fibre
Carbon fibre has long been recognized as a brilliant yet rather unsustainable material – from cradle to grave. While aluminum or steel frames and parts are alloys of mostly aluminum or iron combined with other metals, which can be melted down and reformed with relative ease, carbon fibre is a composite that is both very energy intensive to make and difficult to recycle.
The complexity of recycling carbon fibre stems not only from the material itself but also from the way it’s manufactured – though not all of it is made in the same way. Around 90% of all raw carbon fibre is what’s called PAN-based, and is made by baking the polyacrylonitrile precursor at temperatures of nearly 3,000°C.
But those raw fibres are then used in carbon fibre composites that can vary in their stiffness, carbon content, and surface treatment. In the cycling industry, the two most common types of carbon fibre composites are thermoset and thermoplastic carbon fibre – each with a different polymer matrix.
Thermoset carbon fibres (officially carbon fibre-reinforced thermoset composites), the most widely used type in cycling, are treated, or pre-impregnated, with an epoxy resin before the plies are arranged in a mold and heated under pressure to form the finished product. Once set, it cannot be reshaped – similar to a boiled egg. For it to not lose its stiffness qualities even raw carbon fibre “prepreg” needs to be stored in cool temperatures and if stored frozen at -20°C, its shelf life is at best one year.
Thermoplastic carbon fibre, on the other hand, is treated with a different kind of resin that makes it much more malleable. Its structure is more like cooked spaghetti instead of linear lines, meaning you can reshape it without breaking it. As such, thermoplastic components can be reheated and molded again, which opens up more possibilities for recycling and wastes less of the material in manufacturing. The raw material also doesn’t need storing at very cool temperatures, which leads to a longer shelf life.
Thermoset carbon fibre has been used and refined over decades, making it well-understood and highly evolved in the ways it’s manufactured. Thermoplastics offer a lot of benefits, but for the cycling industry to take full advantage these would require a complete overhaul of how carbon fibre frames and components are manufactured.
The other aspect has to do with concerns over performance. While thermoplastic carbon fibre is theoretically more sustainable, it tends to be heavier and offers a different ride quality than thermoset. As such, each material presents unique challenges and opportunities for the industry – and recycling.
How can carbon fibre be recycled?
Thermoset carbon fibre is composed of long, extremely thin strands of carbon reinforced by the polymer matrix of the resin. Recycling this composite is not a matter of merely grinding it down and reusing the materials. To reclaim the fibres, they must be separated from the resin without damaging them, which involves energy-intensive processes like pyrolysis, super-heated steam or solvolysis. In the process, the resin can also end up being a waste product, but we’ll touch on this later.
Pyrolysis involves burning off the polymer resin at very high temperatures in a controlled, inert environment to avoid excessive damage to the fibres through reaction with oxygen, while solvolysis uses chemicals to dissolve it at lower (but still hot) temperatures. Neither of these processes is without trade-offs, but because virgin carbon fibre is expensive, there is both an economical and environmental incentive to find a way to recycle the material, even if it requires a lot of energy.
“If we are able to use substantial quantities of reclaimed carbon fibres into a second life structure, then we reduce the carbon footprint for the fibre substantially,” explains Ian Hamerton, Professor of Polymers and Sustainable Composites at the University of Bristol and the National Composites Centre (NCC). But here comes the problem: the reclaimed fibres are far from perfect.
Even in the most advanced recycling methods for carbon fibre, the material often gets downcycled or used as a filler material for example in road or building construction materials, or in the context of cycling, things like tyre levers, pedal bodies and brake lever blades.
That is largely due to the way the pyrolysis or solvolysis used to extract the fibres from the resin creates an end product that resembles something that’s come out of a plush toy rather than a high-quality composite material with high tensile strength. “The fibres you get out are tangled like cotton wool,” says Hamerton.
“So they’re quite discontinuous, they’re quite randomly oriented. If you are going to use those in the second life, they are usually used in a disoriented or misaligned fashion. And if you do that, the mechanical properties you expect from the composite and second life are much lower.”
Thermoplastic carbon fibre can be similarly recycled by either pyrolysis or solvolysis, but because the thermoplastic polymer binds the fibres less tightly than in a thermoset, this process requires a lot less heat. But most importantly, because of its re-moldability, thermoplastic carbon fibre can also be shredded into small pieces, which can be then compression molded to be part of a new product. In very simple terms thermoplastic carbon fibre recycling a carbon fibre-reinforced thermoplastic composite could mean that if you took a part of a thermoplastic frame you could mold that into a mudguard, for example.
In addition to reclaiming the carbon fibres from the composites, another important advance is in the resins; normally a waste product in the recycling process, new technologies have created resins that can themselves be recycled in pyrolytic and solvolytic systems. That’s part of the shift Hunt used in its H_Cyclo wheels, changing the normal resin to a recyclable one called EzCiclo – a simple swap that required no change in the manufacturing tooling. While the product still needs to be recycled in the same way as any other thermoset carbon fibre, the temperatures required to separate the resin and fibres are much lower and the resin itself can be reclaimed and reused multiple times, improving the circularity of the product.
The new types of resins are more expensive and have shorter shelf lives than the non-recyclable ones, which is perhaps why they are not widely adopted yet. Trek also told Escape it’s currently experimenting with recycled and bio-based resin systems, produced from biomolecules such as sugars.
Why is thermoplastic carbon fibre not more widely used?
Despite its undeniable positives when compared to thermoset carbon fibre, thermoplastics are a niche product in the cycling industry, and much of that is down to its different performance qualities. Patrick Brown, a development engineer behind the new H_Cyclo wheels at Hunt, explains that thermoplastic carbon fibre simply didn’t meet the company’s stringent impact test criteria.
“We’ve tried thermoplastic stuff and tested it. But for us, we couldn’t hit our impact test criteria with the products that we were testing. You get a different ride feel from it, and it wasn’t a product that we wanted to make. The advantages of a thermoset are that in practice it’s lighter and it’s stronger – so that’s a route that we wanted to stay down because we don’t want to make the customer sacrifice performance,” Brown says.
This sentiment isn’t universal, but is echoed widely in the industry. Parcours, another British wheel manufacturer, has explored thermoplastic carbon fibre but found similar drawbacks. Founder Dov Tate emphasises that sustainability is important, but the practical reality is that performance still drives consumer demand.
“You might get early adopters or principle-driven customers, but the vast majority are just going to go for something that’s either cheaper or better. So we need to make it either cheaper or better because, you know, as much as we as an industry can make it, people have got to buy it too,” Tate explains.
Despite the hesitation toward thermoplastic carbon fibre, it’s been trialed as an option for a long while. Two decades ago, brands were already experimenting with the material; companies like Schwinn, Yeti, GT, and K2 all had a go at creating thermoplastic frames, but as we now know, none of these were truly successful.
More recently, Joe McEwan from Starling Cycles – a mountain bike brand solely specializing in steel bikes – was part of a project that trialed a thermoplastic carbon fibre bike in 2022. The project, in short, didn’t succeed, and McEwan said he doesn’t see it being feasible or adopted in large-scale manufacturing in the near future.
“I think at the moment, the technology is just not there – they don’t know how to make bikes out of it. You have to make them in a slightly different way, and they’re not set up to do that,” he says. “And the consumers just don’t care, do they? People just want a carbon bike. Making a carbon fibre bike is like the McDonald’s of manufacturing. The bike industry is in this position where there’s this perceived value to carbon fibre bikes, and it’s cheap to produce once you’ve paid for the tooling. So they just keep knocking them out, and they’ve got no incentive to change it.”
Thermoplastic success stories
Despite the industry’s hesitance and those early and unsuccessful attempts, thermoplastic carbon fibre has found a foothold in cycling. US-based CSS Composites produces thermoplastic carbon fibre wheels made with what it dubs FusionFibre. The material, used for wheels sold under its own Forge+Bond label and by brands such as Chris King and Bontrager, is claimed to have an indefinite shelf life and is more easily recyclable due to the different epoxy blends. CSS claims their wheels are fully recyclable and even “zero-waste” – if they are indeed recycled.
Similarly, Belgian company Rein4ced is making thermoplastic carbon fibre frames at an automated factory. Rather than focusing solely on sustainability of the material, the company has taken durability as its main selling point and claims that its “Feather” composite is much less brittle than regular, thermoset carbon fibre and as such, can create a bike that is “unbreakable.”
Rein4ced’s factory has already produced several prototypes for brands such as Ghost, and a production enduro mountain bike for Kellys. Rein4ced founder and CTO Michaël Callens says he’s confident there is no performance or weight drawback to the thermoplastic material.
“Kellys has the same model in its lightweight lineup which is a thermoset one, so we can directly compare them in performance. So that’s why we know we compete quite well,” Callens says. The main difference in Rein4ced thermoplastic carbon fibre is the incorporation of steel into the composite – something that could at first feel counterintuitive from a weight perspective, but which, as Callens notes, can also make the composite less brittle and more tunable.
“Steel has an interesting feature in that it has roughly the same stiffness as carbon fibre. In absolute terms, it weighs more, but it has the same stiffness,” he says. “And as opposed to other manmade fibres, you can tune the strength and how far it can elongate independently of the stiffness. Whereas with carbon or, for example, Kevlar fibres, if you make it more ductile (capable of being drawn into thinner rods), it will automatically also become less stiff. Or you really stretch the molecules and make them very aligned, and it’s very stiff, but also brittle, so this is a trade-off – and you don’t have that with steel.
“And that makes it interesting, because we’re combining fibre types. Combining something very ductile and something very brittle is not necessarily new, but because we combine two fibres which are approximately alike and then one can be stretched more than 10 times more compared to carbon. You don’t need that much steel to still have a factor on the impact, and that’s how we can cope with the weight as well.”
End of life challenges
As promising as something like the Rein4ced’s Feather material might sound for a product’s durability, all these technologies still have their end-of-life sustainability challenge to overcome. The UCI estimates that most carbon fibre cycling equipment has an average lifespan of just three years and once a frame or wheel is discarded, the chances of it being recycled are slim regardless of the material unless an effective recycling system is in place. That’s why simply saying something is recyclable doesn’t mean much.
It’s a problem that Rein4ced’s Callens also recognises.
“We really don’t want to say [the Feather composite] is recyclable if there’s no solution yet. That’s why we focus on putting recycled material in every new frame that we sell, because that way you reduce the environmental footprint that you make. The added bonus that at the end of life, somebody in the longer term can still do something with it is nice, but it needs the supply chain [to work].”
One of the industry-wide obstacles to recycling carbon fibre in the cycling industry is the lack of recycling facilities. In an ideal world, recycling carbon fibre doesn’t require shipping the recyclable items to the other side of the world. But even for Hunt – the lone cycling company to create a defined recycling process for consumers alongside its theoretically recyclable product – that’s not possible. At the moment, the recycling infrastructure for cycling parts isn’t quite there – nowhere in Europe or North America processes the EzCiclo resin Hunt uses, for example.
“Currently the recycling infrastructure isn’t there for this product – we’re quite open with that. There’s currently one Asian recycling facility, and there’s maybe a carbon cost to get that product back there,” Brown from Hunt says.
It’s unclear when that will change. The EzCiclo resin that Hunt’s new wheels use has also been adopted on a much larger scale by a Spanish-German wind turbine manufacturer Siemens Gamesa. That could drive quicker adoption of recycling, but Kasper Jalander, who works for Bjorn Thorsen, a Danish chemical manufacturer that sells the EzCiclo resin to the European market, highlighted that while the drive to be more sustainable in manufacturing is growing in the wind industry, its timescales are vastly different to those of the bike industry.
Wind turbine blades that use recyclable resin are designed to be in use for an average of 20 years, he notes. With such a lifespan, the industry can incorporate a new manufacturing process with a claimed recyclability element without worrying about the instant need for recycling facilities.
That said, Brown also noted there are plans for a recycling plant in Romania by 2026 and another in the US. But until then, recycling the H_Cyclo wheels requires sending them first back to Hunt, who will then ship them back to Asia.
Is calling carbon fibre back possible?
Still, Hunt’s program is more fully realized than most others in the bike industry – and more than one company told Escape they are hesitant to call their products recyclable because they cannot guarantee the call-back system for them. Yet, with the amount of carbon fibre waste material created in the industry, it’s evident that some sort of system is needed.
Specialized and Trek launched carbon fibre call-back schemes in 2011, and after a year Trek reported it had collected 70,000 lb (31,750 kg) of carbon fibre frames and parts it could potentially recycle (though it’s unclear how). Neither call-back scheme ever ran globally – the Specialized program now operates in the US – and even as a big player in the industry, Trek is clear in pointing out how difficult setting up something functional is without the whole supply chain on board.
“We are applying pressure to the material suppliers to begin take-back programs,” says Joel Demeritt, Trek’s US sustainability manager. “Please note that aerospace, power generation, and automotive completely dwarf bicycle and sports equipment manufacturing in terms of material consumption and disposal volumes. It is extremely difficult for Trek to have a meaningful takeback program from our seat. We have loads of suppliers saying, ‘This is recyclable/circular,’ or, ‘This is a resource at the end of its life.’ OK … so then why don’t they have programs to recover that material?”
Demeritt is right that sports and the cycling industry are a drop in the ocean; a 2023 study from the University of Sydney estimated that the “annual accumulation of CFRP waste from aircraft and wind turbine industries alone is projected to reach 840,300 tonnes by 2050.”
With no large-scale systems in place, the recycling is left to the small players and manufacturers to organize. Forge+Bond, with its manufacturing based in the US, said they are not shipping their wheels to Europe due to the high cost and, when it comes to recycling the wheels: “If the wheels break we do ask for them back so we can recycle and turn them into chop compression molded parts. It’s how our business is set up to succeed. If we fail to use the wheel at the end of its life we lack material for other items that provide revenue,” a brand representative told Escape. Those wheels would need to get to the American CSS Composites factory first, though.
Recycling in this instance rarely means the wheels getting a new life as wheels; rather, the F+B $1,900 wheels end up being $50 tyre levers.
Revel, who also uses FusionFibre says on their website, “Once we receive your wheel, we will remove the vinyl decals and drop the rim into a chipper to chop it into pieces for recycling.”
There are only so many tyre levers we need
With so little carbon fibre getting recycled, when we asked major brands what happens to the carbon fibre parts that might have a manufacturing defect, or need to be discarded at the end of their lifetime, the most common answer was that they get ground down for filler material, sent to incinerators to be burned for energy, or put into landfills.
This is something that happens across industries and materials, not just the cycling world. At more than 16 square miles, Arizona’s Davis-Monthan airbase is one of the largest airplane “boneyards” in the world, where thousands of decommissioned aircraft shells and their metal and carbon fibre parts bake in the sun. The Casper, Wyoming regional landfill has nearly 1,000 carbon and fibreglass composite wind turbine blades that are past their service life. The sheer volume of the wind turbine blades – which in essence never degrade because of the materials used in them – has even led to nations imposing landfill bans on them in the hopes of the industry ramping up the efforts in recyclablity.
The cycling industry is much smaller in scale, but it grapples with similar issues. The industry experts Escape spoke with repeatedly highlighted that for recycling centers, the cycling industry represents such a small share that they are not interested in incorporating the waste into circularity. That is, if those recycling facilities even exist.
“Certainly within cycling, there’s not a demand for that. That’s why you see these kinds of really cool-looking injection-molded tire levers. They’re great, but there’s only so many tire levers you need, versus frames, forks, rims, any other bars, or any other carbon product, because all of those products require tensile performance. That’s the challenge,” Parcours’ Tate explains.
Trek shares Parcours sentiment.
“We currently aren’t pulling carbon composite material from the market to recycle. We do recover warranty items and use waste-to-energy to dispose of them,” says Trek’s Demeritt. “Actual recycling is a difficult logistical and technical exercise, and the options we have for the material are limited. Because the materials require shredding to reprocess, you essentially wind up with a short-fibre material that is equivalent to a highly fibre-filled plastic but magnitudes more expensive and complicated to source. That’s the current state, which is not that great. However, we’ve got projects in the works for reducing input impacts and recycling.”
Those projects include thermoplastics and reducing the impact of the resins and fibres Trek uses in its carbon fibre products – though none of these are quick fixes and Demeritt says very few other users of composite materials are requesting sustainable materials.
Future technologies coming
That’s not to say that recycled carbon fibre is just junk or that we’ll never be able to truly re-use the material in similar products the way we can with metals. Professor Hamerton and his research team are working on a system called HiPerDiF (High Performance Discontinuous Fibre) at the University of Bristol, enabling chopped-up carbon fibres to be rearranged for re-usable composite products, retaining up to 80% of the original stiffness, even when the material has gone through five or even six recycling cycles.
“Yes, we see a bit of reduction in performance, but still see materials which are mechanically useful engineering materials,” Hamerton explains. “Our ethos is that you produce materials that are highly aligned engineering materials – your second life is more useful, and it’s more valuable as a product. Yes, there’s an offset – you have to deal with an offset in stiffness, but you design around it, as opposed to saying, ‘Well, I can’t do anything more with it. I can only use it as a bench, yeah?’ You know, it’s gone from aircraft to bench. That’s all I can do with it. Here we are going through amore realistic cascade of use.”
In Bristol, a company called Lineat is using the HiPerDiF technology and has already been involved in a project with Scott Sports that looked into giving bike frames a second lifecycle as skis. Granted, Scott’s sustainability manager Andrew Goodman said, the process didn’t come without its niggles.
“The reason why we went for a ski and not something else is that the [carbon] tape wouldn’t perform to the same level as some of the other fibres,” he says. “We could have used tons of it to make a product or prototype, but we decided to put it in a ski so that we could really just showcase what that recycled carbon fibre could look like in a product in a ski. The good thing was the ski skied. But it didn’t ski very well on the first iteration.”
Goodman said that the first iteration of the tape from Lineat was a little too narrow, and because it needed to be handled differently the manufacturers needed to be educated that while the tape looked like carbon fibre, it wasn’t what they’d got used to.
“We went back to Lineat and said, ‘Listen, we need something that is more in line with what is currently being used inside our supply chain, so that we don’t have to teach new skills, find new manufacturing processes. It has to be a bit of that plug-and-play kind of solution.’ And so, we did a second iteration when they produced a tape that was a bit thicker, a bit wider. And here, we put it in a ski again and it worked out actually quite well.”
The above Bike to Skis initiative was part of the Carbon Fibre Circular Alliance’s Carbon Fibre Demonstration Project, where the UCI partnered with Scott Sports to create the prototype for demonstration purposes. Goodman said that although the Bike to Skis project is complete, they continue to collaborate with Lineat to incorporate the technology into other products. The Carbon Fibre Circular Alliance has entered phase two and is now looking at introducing more recycled carbon fibre targets to showcase at the Olympic Games in 2028.
The HiPerDiF – and other similar technologies – aren’t quite there to be used for full bike frames or wheels yet. Escape was informed that Lineat is working with more than one cycling partner to incorporate the material into products, even if it’s only partially. All of that offers hope that change in the carbon fibre manufacturing industry is possible.
“Patagonia when they started using recycled polyester some 30-odd years ago, it wasn’t the same quality. It wasn’t as good,” Goodman notes. “But now you bring out a product with recycled polyester instead of virgin polyester, and most people who are not in the technical apparel industry and textile experts will never see the difference between them. So maybe in the future we’ll see more of that – where the recycled version has grown to be comparable to the virgin one. But in our day and age particularly, when it comes to prepregs or thermosets, we’re not there yet. There’s still a lot of work to do.”
Are there any other ways for change?
With pro cycling heavily influencing consumer trends, some argue that governing bodies like the UCI must take a more active role. Whether through mandating sustainable materials in racing or collaborating with governments on recycling initiatives, change will require coordinated efforts across the industry.
Most in the industry are skeptical about this becoming reality. While UCI might find ways to inspire some change around circularity and carbon fibre, it’s going to be hard to perform a mind shift for the riders who are used to having the lightest, stiffest, and most high-performance equipment there is. The UCI didn’t respond to a request for a comment on this matter.
Talking with the experts, it was apparent that the current focus was on producing products that have a competitive performance advantage, as well as something that other products on the market don’t have – all at a competitive price. It seems that even though the industry does from top to bottom recognize the unsustainability of the material, it has got itself so deep into the chase of the lightest, most aero and best-performing carbon fibre products that it’s left behind materials that offer better recyclability. Similarly, the compromise between circularity, performance and longevity could be re-examined. If the industry designs with durability in mind, the products are more likely to be sustainable simply due to the longer lifespan.
But ultimately all products reach an end, and then the issue is how well, if it all, they can be re-used in new ones. “I think if this is a question about recycling I can say here that you cannot recycle carbon fibre. You cannot do it – you can repurpose it – but you cannot recycle it,” says Starling Cycles’ McEwan. “Recycling to me is: it can go in a loop forever, whereas every single time you do something to carbon fibre the next use of that product is being degraded. So it’s getting worse and worse every time. Whereas steel, you’ll take a steel bike and you take it to the scrapyard, and they can melt that steel down and turn it into another bike, so it can be a cycle, whereas carbon fibre isn’t.”
Ultimately, the industry must find a balance between performance and environmental responsibility. And that is likely going to take a while.
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