UD, 3K and 12K are just three different weaving types of carbon fibers that are widely used for manufacturing bicycle products.

There are lots of debates online about the difference between carbon weaves of UD, 3K and 12K. People who are just new to carbon fiber products maybe not know much about it.

UD is short for Uni-Directional, the fibers of UD weave are arranged in one direction, which is the most frequently used to make carbon fiber products. 3K means there are 3,000 filaments per “tow”, 12K means there are 12,000. They are decussated like a web. 3K weave carbon fiber is most well known.

The different weaving way makes the carbon fibers in different appearance and performance.


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 the pattern.


Basically, for carbon fiber rims, we don’t discuss the strength between different weaves, since the strength in different weaves shows almost the same. Rims in different weaves are just different in the outer layer carbon fibers. Inside of all different weave rims, are mainly UD carbon fibers. We usually only consider different weaves are just to show different appearances.

However, they still have differences in performance.

As we known, carbon fiber layer is a kind of composite material of carbon fibers and resin material that is to bond carbon fibers, and 3K carbon fiber is decussated like a web. So, 3K carbon fibers have a function as a web to filter redundant resin inside of carbon fiber products. When manufacturing bicycle rims, we usually add a layer of 3K carbon fibers inside of rim channel to filter redundant resin, to balance the content rate of carbon fibers and resin material. Another advantage of 3K carbon fiber is that it could protect the spoke hole from flaking when drilling it. That’s why we like to add the layer of 3K weave fibers inside of rims. The advantage of UD carbon fibers is the strength. That’s why we make all rims with UD fibers to support.

Additionally, there’s a thought saying that in theory is woven fibers like 3K as the outer layer on a rim has a better impact strength, but there isn’t a real experience or test could support this standpoint.

As all presented above, no matter UD 3K or 12K weave rims, inside is mainly composed by UD fibers and a layer of 3K fibers. MAX-BMX team makes all carbon fiber products in high performance, no matter what weaves they are applied as an outer layer. It’s not quite necessary to discuss the performance of a rim in which weaves. May customers feel free and choose the weave you love.