Material: What is carbon?

8. August 2018

Category

All you adventurers out there have surely heard of carbon. After all, it is used in all kinds of sports equipment and is celebrated by many a gearhead because of its lightness and stiffness (not strength!).

If you have any questions as to the reasoning behind this distinction, you should definitely read on. In this post, we’re going to take a deep dive into carbon, describing its properties, composition and advantages and disadvantages as compared to materials that tend to be cheaper, such as aluminium.

What is carbon anyway?

Carbon Materialinfo

Carbon is stiff and lightweight, but not necessarily more durable. This means that the material hardly reacts to mechanical impulses, but tends to fail with sharp, jagged breaks when under high stress.

Lightweight carbon is a becoming more and more popular option for all kinds of sports equipment. The word carbon comes from the Latin word for coal (carbo) and refers to the chemical element carbon. Carbon is pretty important stuff. Without it, the earth would be nothing more than a rock without any biological structures – so obviously no humans either. In other words, you could consider the carbon used in our outdoor gear to be a natural material, at least if you look at it over its long process of transformation. Coal’s carbon comes from an array of different substances, but most notably from decomposed plants, from which petroleum is derived. And it is petroleum, which consists of several hydrocarbons, that serves as source material in plastic production.

Admittedly, this isn’t the whole story and really only half the truth. What we colloquially refer to as carbon actually only consists in part of the wafer-thin carbon fibres. That’s why, it would actually be more correct to say: carbon fibre reinforced polymer(CFRP). Still, this doesn’t really explain what carbon is. So, let’s get even more specific and talk about what carbon is made up of.

What is carbon made of?

For a start, allow me to mention that what we commonly referred to as carbon is a combination, with the only the fibre bit consisting of carbon and the rest of other chemicals. In other words, it’s a composite material. To make things even more complicated, composites of CFRP and GFRP are also treated as carbon. GFRP is short for “glassfibre reinforced plastic“.

The carbon fibres/glass fibres are combined with a matrix, usually a polymer resin. The matrix serves to bind the fibres together in grid-like structure and fills in the gaps. A common polymer resin is epoxy, which is a thermoset resin, which contains all sorts of chemical elements, but no carbon fibres. To put it simply, thermoset is a plastic that is not malleable after curing by means of heat and can withstand high mechanical stress.

Carbon is stiff but not necessarily high strength

Don’t worry, we’re not going to give a lecture on the science of this material, but we are going to delve just deep enough to ensure that you have a basic understanding of the properties of carbon equipment. This will then enable us to compare carbon to other materials, such as aluminium. Whilst the carbon fibres add high strength and stiffness to the composite material, the matrix prevents the fibres from shifting against each other when under stress. Since the composite material is only really stable in the direction of the fibres, the fibres are usually laid out in different directions.

These complex patterns are what gives carbon the stiffness it’s known for. Stiffness is, however, not to be confused with strength. The former describes a high resistance to (elastic) deformation – the material does not vibrate or move under increasing stress, but then breaks apart abruptly under high stress. Strength, on the other hand, is the resistance to mechanical stress. A material that is very stiff does not necessarily have to be strong, and can in fact be easily broken.

Carbon is not always carbon

Since there are various carbon composites and fibre arrangements, all of which produce different tensile, compressive, impact and breaking strengths as well as different levels of stiffness and damping properties, it is very difficult to get an idea of the exact construction and properties of the carbon used, independent of the manufacturer’s specifications.

The complicated composition of carbon not only makes it less transparent in general but also more expensive than similarly durable metals. So, why opt for carbon over aluminium, when the latter seems to have all the properties you would want? Well, when it comes to sports equipment such as walking poles, road bikes or fishing rods, you need an extremely high level of stiffness at the lowest weight possible. And here, high-quality carbon is second to none. Wait, high-quality carbon? Doesn’t that imply that there’s an inferior kind of carbon?

Low-quality carbon may be rare, but it does exist. And, contrary to popular belief, high-quality carbon doesn’t necessarily have the highest amount of carbon fibres, but the best composites in the best matrix. Here are some examples: To have a pole made of „100% carbon“ would be overkill because although it may be ultralight and stiff, it would also break quickly because of how brittle it would be.

80-90% is ideal, as it provides both stiffness and damping properties along with breaking strength. 60-70% carbon usually means an increase in weight but also more stability (and a more affordable price tag). If a pole has less than 60%, there’s really no advantage over aluminium poles in an identical or lower price range, according to experts.

However, the percentage alone does not determine the quality of a product. You’ve got to have additional information and at least some expertise in order to determine other important contributing factors. Fortunately, though, you can rely on manufacturers such as Leki or Komperdell to use high-quality materials. As long as you don’t opt for some cheap model at a random discount store, you can generally expect your poles to perform reliably in normal conditions. You’d really have to get majorly stuck between some massive rocks or roots to break a high-quality pole.

Carbon vs. aluminium

Simply put: Aluminium is harder to snap, whilst carbon is stiffer. In other words:

Aluminium vibrates under stress and is unlikely to break under high stress, whilst carbon tends to fail with jagged breaks.

In theory, the slower buckling of aluminium is less dangerous in the event of a fall. However, this only applies in situations where an average adult’s entire body weight falls abruptly on the pole. But no need to worry: As long as the walking poles aren’t some cheap knock-off, they can only snap as a result of unfortunate lateral pressure applied during uncontrolled movements on loose ground.

However, caution is advised when the poles are extended to nearly full length, especially when it comes to aluminium poles because it can have a negative effect on their stability. For this reason and because of their better shock absorption, high-quality carbon poles are recommended for Nordic walking, which is popular among heavier individuals. In general, tall or heavier outdoor enthusiasts should opt for more stable, high-quality and slightly heavier poles.

Neither is better – just different

Carbon Materialinfo

In theory, the slower bending of aluminium is less dangerous in the event of a fall.

Whilst carbon and aluminium poles have approximately the same breaking strength and stability, the carbon models have a slight advantage when it comes to their weight, namely about 10% as compared to their aluminium counterparts. And, this is reflected in their higher price. When it comes to basic models for beginners, aluminium seems to be the better option, mostly because of the lower price tag. But, these are just estimates based on the options we have available in our shop. Also: the lighter your poles are, the better the handling will be and the slower you’ll fatigue.

Another factor is water: If you consider the fact that aluminium poles tend to corrode when exposed to water and should be taken apart and dried after walks in the rain, one could think that you should opt for carbon instead. But this is not necessarily the case. Carbon is not necessarily better than aluminium. For example, alpinists who often travel on rough gravely terrain, (good) aluminium poles would be the better choice.

Since the advantages of carbon and aluminium are not mutually exclusive, several manufacturers like Leki or Black Diamond use both in the same model to achieve the perfect balance between things like stiffness and robustness.

Of course, the balance of advantages and disadvantages of carbon varies depending on the type of equipment. Because of the malleability of aluminium, carbon would be the much better option to use as a stabiliser in the sole of your ski touring boots or the upper on your cycling shoes than aluminium ever would be.
We hope this article has shed some light on carbon!

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