Disadvantages of carbon fiber composites include their high cost in comparison to other materials like steel, aluminum or wood. Carbon fiber is also more brittle, and thus less impact resistant than some other materials. It can be difficult to repair when damaged and requires highly specialized repair techniques.

The strongest composite material is subjective and depends on the specific properties required. While carbon and glass fiber reinforced polymers offer high strength and stiffness, other composites such as ceramic matrix composites and metal matrix composites can offer enhanced heat resistance and durability.

Carbon fiber composites can typically be more expensive than traditional materials such as steel or aluminium. This is due to the complex manufacturing process, the cost of the raw carbon fiber, and the specialized skills required for handling and fabrication. Despite the cost, they are preferred in certain industries for their superior properties.