Bicycle wheels are one of the most important components of a bicycle. If you want to upgrade your bike, many people probably think of replacing the wheels with carbon ones first. This is because carbon wheels are very effective in improving the ride quality. If you look at the bikes of professional riders, you will notice that they all ride beautiful carbon wheels. But have you ever asked yourself how carbon wheels are made? In this article, I would like to explain how wheels are made as simply as possible. For most of us, the manufacturing of carbon wheels is a mystery, so let's take a look.

What is carbon fiber?

Carbon fiber was developed from the aerospace industry. It is made of loose fibers consisting of carbon atoms, which are suspended in resin to create a solid material. Carbon fiber is a fiber with a diameter of about 5 to 10 micrometers, consisting mostly of carbon atoms.

Carbon fiber rims are composed of two components: carbon fiber and epoxy resin. When molding carbon wheels, pieces of prepreg carbon are placed in a mold. Prepreg is raw carbon fiber impregnated with epoxy resin.

Carbon fiber offers various advantages, including high rigidity, light weight, high chemical resistance, high tensile strength, high temperature resistance, and low thermal expansion.

How are carbon wheels made?

First, the rim is designed using a special 3D program. Here, the required carbon fiber and the necessary shapes for laying the carbon fiber can be calculated in detail.

We source sheets of the highest quality Toray T700 and T800 carbon fiber. This is also called prepreg carbon. Prepreg is raw carbon fiber impregnated with epoxy resin. The second item we source is high-quality airbags. We choose these airbags because they result in much smoother rim walls. All raw materials we receive undergo a strict inspection with a DSC tester to check for any abnormalities.

After the initial inspection, the carbon fiber is stored in a refrigerator unit at -5°C. This is necessary to maintain the activity of the resin.

The next step is to cut the prepreg to the desired length, shape, and angle (cut with our own CAD-controlled device) and then lay up the carbon fiber within a custom-built mold.

Accuracy is critical at this stage of the process, so the layup is done by hand by experienced layup workers.

The next stage is hot press molding.

The carbon needs to be cured at a considerable temperature and permanently controlled to give it its strength.

Our hydraulic molding machines are specially designed and PC-monitored for pressure, temperature, and time to ensure we always deliver the highest quality. After heating, they are cooled, and after demolding, the wheelset undergoes its first raw finish quality control.

The next step is removing the used airbags. We use a unique process to extract the airbags through the valve hole. The rim then goes to our drilling machine, where we use a computer-controlled CNC drill to create spoke holes in 4D directions.

To ensure all holes are drilled correctly and the rim surface is intact, the rim undergoes a second quality control. We also inspect the roundness and flatness of the wheel at this stage.

In the next stage, the rim is ready for the paint shop. Paint covers and protects the carbon. Our experienced staff smooths out small imperfections and applies a special treatment to the rim surface.

In the final stage of manufacturing, after painting and decals, the wheels truly come to life. They are hand-laced and trued by our wheel builders to undergo final quality control. Our wheels are inspected one last time. This includes front stiffness tests, lateral stiffness tests, and impact inspections to meet all ISO standards.

After the wheelsets are inspected, they are recorded in a database, and each carbon rim is assigned a unique ID number. All that remains is the careful packaging process.

Finally, let's summarize the manufacturing process of carbon rims.

Designing the rim in a 3D program.

Sourcing sheets of carbon fiber. Performing strict inspections with a DSC tester.

Storing in a freezer unit to maintain resin activity.

Cutting prepreg to desired angles and shapes.

Hot press molding using a PC hydraulic molding machine with pressure, temperature, and time control.

Raw finish rim quality control (QC-1).

Removing airbags from valve holes using a unique process.

Drilling holes in 4D directions using a PC-controlled drilling machine.

Quality control (QC-2), checking and inspection.

Smoothing and surface treatment by experienced staff.

Painting and decaling.

Quality inspection (QC-3), 100% quality inspection, recording in database.

Each carbon rim has a unique ID number.

Packing, each carbon rim is carefully packaged.