High Modulus Frames – Are they better?

Low Modulus carbon fibres are recognised as the most common and cost effective fibres to produce, these are less stiff but strong once laid up with epoxy and cured. Whereas High Modulus carbon fibres will produce a part which is much stiffer, but not quite as strong.

How High Modulus Carbon Fibre is produced?

Carbon fibres start from some sort of polymer – which is essentially just a long chain of carbon atoms with other elements, such as hydrogen and oxygen, poking off the sides. The polymer is then heat-treated at very high temperatures.

This process removes all of those oxygen and hydrogen atoms and what you’re left with are the carbon atoms which have a very good bond strength

It’s this heat-treating process that determines whether a carbon fibre is high modulus or low modulus. The higher the temperature and the longer you heat treat it, will make the fibre even more pure and have a better carbon crystalline structure. This gives the carbon a higher modulus but with the temperatures and lengthy heat treating process, it’s also more costly.

When talking about carbon frames, it’s never actually pure carbon – it is a composite material, with resins to bond the carbon fibres together.

Manufacturers might use more standard and intermediate [i.e. lower modulus] fibres in high strength areas of the frame, giving the most optimised stiffness, strength and weight in the final product.

So a wide range of high modulus, intermediate modulus fibres and sometimes standard modulus fibres are used in all carbon bikes, and it’s all about putting the high stiffness and high strength fibres where they’re needed most. We usually see a combination of different carbon fibres that are used in most high-end branded frames because they are trying to optimise those characteristics of strength and stiffness.

It is never a simple subject but hopefully you can understand a bit more when someone tries to bamboozel you with jargon!