Carbon fiber has redefined what performance means in cycling, but how exactly is a crankset or handlebar made from this advanced material? The process behind carbon components is as critical as the design itself, and mastering it is what separates premium brands like QO, ROTOR, or ENVE from the rest.
From Rolls of Fiber to Prepreg Sheets
Everything starts with raw carbon fiber, often imported from aerospace-grade suppliers. These fibers are woven or aligned into unidirectional sheets and then pre-impregnated with resin, a phase known as prepreg. This resin controls stiffness, toughness, and heat resistance.
Each component design dictates how many layers, what fiber orientations, and where reinforcements are placed. For crank arms, for example, a brand like QO might use high-tensile unidirectional layers on the outer faces and multidirectional reinforcements near the spindle to withstand torque and shock.
Layup and Molding: Precision in Layers
The next step is manual layup, where technicians carefully stack prepreg sheets into molds. The layup schedule (which direction the fibers go in each layer) is critical. It defines stiffness, compliance, and durability.
Once laid up, the mold is closed and the component is cured under heat and pressure in an autoclave or heated press. Some brands use bladder molding for hollow parts like crank arms and seatposts, ensuring perfect compaction without excess resin.
QO’s cranksets are molded this way, balancing minimal weight with high power transfer efficiency. The result is a product that’s light yet incredibly strong, and with no excess material or resin-rich zones.
Post-Curing, Machining, and Finishing
After curing, components are trimmed, sanded, and precision-machined to fit exact tolerances. This step is especially important for bottom bracket interfaces, spindle sockets, and chainring mounts.
Some high-end models are then clear-coated to showcase the carbon weave, while others are painted or textured. Brands like ENVE or THM often emphasize visual perfection as well as weight reduction.
In the end, a finished carbon crankset is the product of hundreds of manual steps and strict quality control, not just material, but craftsmanship.