Aluminium vs Carbon Fibre Frames

Aluminium frames.

Pure aluminium has a low ultimate tensile strength UTS. Aluminium is mixed with other elements to create alloy. There are alloy series such as 5,000, 6,000 and 7,000. To increase their strength these alloys are heat treated. This is a process which favours mass production and economies of scale. It is this mass production which has enabled aluminium frames to be produced so cheaply, but, they do not favour small frame builders.

Because aluminium has a low fatigue limit, manufacturers tend to use ‘fatter’ oversized frames which reduce frame flex and hence the likelyhood of fatigue. This means aluminium frames are not much lighter than the best steel frames. Aluminium is also stiffer which gives a less forgiving ride on bumpy roads.

Aluminium framesets usually weigh between 1.9 and 3.0Kg

Carbon Fibre Frames

Weight for weight, carbon fibre frames are stronger and more rigid than steel. Carbon fibres are layered ina composite material to give strength and ridigidity where it is needed.

An advantage of carbon fibre frames is that the frame can be more easily designed and moulded to maximise aerodynamic advantages. Carbon fibre has more flexibility in its mould and this can give an aero advantage over traditional steel / aluminium frames.

Personal Experience

I’ve ridden both aluminium and carbon fibre frames. What I felt from the carbon fibre frame was the greater feeling of power transfer. There was greater stiffness and rigidity you don’t get with an aluminium frame. But, it’s worth bearing in mind that not all carbon fibre frames are the same. I have Trek Madone 6.9 which is very lightweight and very strong.

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