Plain vs. Twill Carbon Fiber: Know the Difference

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If you're new to the world of carbon fiber material, there are a few terms you will want to understand. The most common – and the first two we'll take a look at – are plain weave and twill. Carbon fiber is also a very versatile material and can be combined with other materials to form composites. One such example is graphene, a single-atom-thick sheet of pure carbon.

Know the Difference

1. It's the latter that's of interest to the carbon-framed cyclist because twill is a sturdier and more impact-resistant type of fiber. It's what's used to make most carbon bicycles, and it's the reason why frames made from the stuff are so stiff and durable.
2. Plain weave carbon fiber is sturdy and stiffer than twill carbon weave.
3. Plain weave gives beautiful interior and exterior parts of carbon fiber products to the industry and holds the place of the second most commonly used of all carbon.
4. Plain weave and twill have different numbers too, though this can be a bit of a minefield for the novice. There's a 'twill count' for each weave, but it's not as simple as saying one equals the other. This is because a plain weave with a given number of weft fibers may have twice as many warp fibers, while the opposite can also be true. In short, the count can only be understood in comparison to other types of fabric.
5. That said, it is possible to work out the rough strength of a given weave by doing some quick maths. A plain weave is generally around 80 percent as strong as a corresponding twill, and a 300-tc plain weave (300 weft fibers per inch) is about the same strength as a 450-tc plain. So a 400tc twill is probably stronger than an 800tc plain, though bear in mind that it all depends on the fiber type, construction method, and whether the weave is unidirectional (UD) or bidirectional.

As a very general rule of thumb, the higher the twill count, the tougher and more expensive the resulting fabric. A 300tc carbon fiber is usually the best value, followed by a 450tc or possibly a 600tc, with anything over 600tc likely to have been over-engineered.

Carbon Fiber Types

We mentioned above that carbon fiber sheet comes in various types, and the difference between these types is determined by the way the fibers are arranged and connected within the finished composite.

1. The most commonly used are called monocrystalline and polycrystalline, which simply refer to whether the fibers are arranged singly or in small groupings, respectively.
2. The second factor that affects the structure is whether the fibers are woven through each other (weave) or stacked and glued together (lattice). In the former case, the carbon fiber is often UD to give strength along the length of the carbon fiber tubes. Still, they can be woven bidirectionally or even woven around a tubular mandrel for maximum strength.
3. Lattice structures have a high resistance to fatigue and a lower weight, but are more difficult to construct. They can be arranged in various ways: honeycomb, hexagonal, and diamond being the most common.
4. Graphene is one of the strongest and stiffest known materials, but it's still expensive and not very widely used in bicycle components.
5. Other composites include boron, aluminum, and magnesium, which are added to provide extra strength or stiffness to the frame.

The last factor affecting the type of structure is the use of Kevlar, Aramid, and Zylon fibers. These are all synthetic fibers, which, when added to the carbon matrix, provide superior resistance to impact.

Carbon fiber's light weight and stiffness are the main reasons it is so widely used. These properties give the material a natural advantage over other materials. However, the strength of a frame is only part of the equation. The material's rigidity allows for precise control over the frame's behavior under stress, which is crucial for good handling. Carbon fiber also has a low density and very strong material. Check out our high-tech choice in the design of advanced carbon composite materials at https://www.nitprocomposites.com.