UD, 3K and 12K are just three different woven types of carbon fiber widely used in the manufacture of bicycle products.

There are many debates on the Internet about the difference between UD, 3K and 12K carbon fabrics. People who are new to carbon fiber products may not know it well.

UD is the abbreviation of Uni-Directional. UD woven fibers are arranged in one direction and are most commonly used to make carbon fiber products. 3K means that each "tow" has 3,000 filaments, and 12K means that there are 12,000 filaments. They are discussed like the Internet. 3K woven carbon fiber is best known.

Different weaving methods make carbon fiber have different appearance and performance.

Weight:

Weave patterns have overlapping fibers, which is why woven fibers are usually heavier than UD. However, the weight differences between the three are slight - about 10 grams. This is negligible considering the error allowance of +/-15g per rim.

Construction:

The weaving of 3K carbon fibers is similar to a spider’s web. To balance the ratio of carbon fiber and resin we often add a 3K layer inside of the rim channel to filter redundant resin. The small gaps inside the 3K layer also reduce the probability of defects on the rim surface. 3K weave also protects the spoke hole from tear-out during the drilling process.

The 12K is the widest weave we offer, and therefore stiffer than 3K. The wider weave costs less in production, the 12K layer is slightly less expensive than 3K.

The UD fiber has maximum strength when running in the same direction. Torsional stiffness and impact resistance are increased as angles are oriented in each layer.

Appearance:

The illustration is as below, it shows different appearances of the weaves, and bicycle rims in different weaves.

UD weave looks like plain black. Crossed 12K weave pattern is 4 times larger than 3K weave.

Customers may also know 1K, 6K, 18K and 24K. They are also decussated/crossed, just in different sizes of pattern.