Carbon fibre is abundant in high-performance frames and bike components. It’s often marketed as aerospace-grade, military-spec, high-modulus, or including some exclusive, secret formula available only to a single brand. But how much of that is real and how much is marketing?
If you’ve ever shopped for a new bike, you’ve seen brands throw around names like Torayca T700, OCLV, Fact 10R, Advanced SL, and BallisTec – but what do these actually mean? Are these unique materials, or just different names for the same thing?
To strip back the jargon, we spoke with carbon fibre suppliers, bike brands, and repair specialists to find out what really makes a difference when it comes to frame quality, performance, and also, durability.
What a carbon fibre frame is
Before we get into what different types of carbon fibres are out there, a quick recap of what carbon fibre-reinforced composite frames are made of. Even though we often refer to them as “carbon frames," they are, in fact, made of a composite material consisting of two things: carbon fibres and epoxy resin, which binds those fibres together.
We've had a look at how the process of frame-making works at places like Argonaut and Bridge Bike Works, but there's a lot to cover before we even get to that frame-building stage.
Most, though not quite all, modern carbon bike frames are made using thermoset carbon fibre composites. This means the carbon fibre is combined with a thermosetting resin that hardens permanently when heated during the curing process.
Carbon fibre frames are cured under heat and high pressure. This means placing the frame (or part) inside a big metal clamshell mould where compressed air in a bladder or, alternately, a mandrel, creates interior pressure.
Unlike thermoplastic carbon, which can be reheated and reshaped, thermoset carbon is irreversible once cured. This makes it lighter and stiffer, but also very difficult to recycle because separating the fibres and resin without destroying their usable properties is complicated.
One of the most important things to understand about raw carbon fibre is that most of it – especially in the cycling industry – comes from a small handful of suppliers. Despite claims of proprietary materials and exclusive technologies, the reality is that the majority of bike brands source their supplies from the same carbon fibre supermarket, so to speak.
There are several dozen companies worldwide – typically in Asia – that make carbon fibre, but the market is dominated by a far smaller number. “Essentially, there are three main suppliers in the world of carbon fibre. There's Toray, Mitsubishi, and there's Toho [Teijin]. And essentially, they all produce relatively similar materials,” Rob Gitelis, CEO of Factor Bikes, explains. “For Toray, most of their business is making materials for airplanes. Toho is much more involved in wind energy and Mitsubishi kind of plays in every field, but I would say they're probably a little more involved in the car space – as is Toray. Those are the three main ones.”
In addition to these big suppliers, there are also producers like Solvay, Teijin, Nippon and US-based Hexcel, who are often involved in the bike industry to some degree, but not as extensively as the three others.
Each of these companies produces raw carbon fibre – such as Toray's T700 or M35J, as well as so-called prepreg carbon fibre, which is the raw fibres mixed with a resin into a sheet. Raw carbon fibre comes in what's called a tow or roving, where many individual filaments are combined to create what looks essentially like a wide, flat yarn or tape and is wound on a spool. To make a pre-preg, material from dozens of spools is combined into a flat sheet that is then treated with the resin. Prepreg sheet can be unidirectional or woven, but in the bike industry, woven prepreg is used mostly for cosmetic appearances; carbon gets its strength from its unidirectional properties.
Raw carbon fibre can be made via several different production processes and "precursor" materials, including what's called pitch-based fibre (made from coal pitch), but the large majority of carbon fibre made today is a type called PAN, the acronym for its precursor material, polyacrylonitrile fibre. They have different properties, but generally, the production processes are the same across different manufacturers.
“It's funny to me when I hear people talking about we use Toray T1100 or something like that. I'm like, 'What does that mean?'” Gitelis says. “You're not talking about modulus and you're not talking about the overall resin content, FAW [fibre areal weight], or anything. You're just saying a standard material. And then it's even funnier when they say this is exclusive to us. And I'm like, 'No it's not. Anybody can buy it.'”
If nearly anybody – as Gitelis says – has access to the exact same carbon fibres, what do Trek’s OCLV, Specialized Fact carbon, Giant Advanced SL, and Cannondale BallisTec mean, then? In essence, these are the brands' marketing terms and not actual grades or brands of carbon – yet, the frames are far from the same.
For example, Cannondale told Escape Collective in an email response that they use primarily Toray and Mitsubishi because they’re acknowledged leaders in the field, with the most advanced tech and proven track records, with the added bonus of being geographically close to the brand’s manufacturing operations. But Tom Heng, Cannondale’s director of design engineering, also admitted that if a product from another manufacturer has properties that will better help them achieve more desired results, they’ll source that material.
“We generally don’t bother to talk about the carbon brands or grades we use in our carbon construction because it’s not really relevant. It’s an oversimplification of a complex process and a distraction from what matters the most, which is the engineering that goes in and, especially, the results that are achieved,” Heng says. “Each frame uses a variety of different fibre types, layered and oriented to deliver specific results. The artistry lies in knowing exactly what results you want – what kinds of stiffness or compliance you need in each part of the frameset to deliver the desired ride feel and what durability and strength metrics you need to confidently offer our lifetime frame warranty. Two different manufacturers can use the same mix of materials yet end up with wildly different results.”
The secret ingredients
As Heng says, even if the manufacturers shop at the same carbon fibre shop, their finished frames can be vastly different, due to the number of carbon fibre and resin options and combinations available. Not to mention, how these are combined in the final frame layup also makes each process more nuanced than it first appears.
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