What does 3K,12K and UD mean?
Uni-Directional (UD), 3K, and 12K are three different weaving styles of carbon fibers commonly utilized in the production of bicycle products. The different weaving way makes the carbon fibers in different appearance and performance.
UD, also known as Uni-Directional, involves arranging the fibers in one direction, and is the most commonly utilized method for creating carbon fiber products.
The main difference between 3k and 12k is roughly how many individual fibers there are per “row” of the weave, also called the tow. 3K refers to 3,000 filaments per tow, while 12K refers to 12,000 filaments. These filaments are crisscrossed to form a web.
Appearance difference
The image displayed below shows matte finish bicycle rims in different weaves. The UD weave appears plain and black, while the crossed 12K weave pattern is four times larger than the 3K weave.
Performance difference
Basically, for carbon fiber rims, we don't discuss the strength between different weaves, since the strength in different weaves shows almost 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.
The UD fiber exhibits its highest strength when aligned in the same direction. Torsional rigidity and resilience to impact are enhanced as the angles of orientation are varied in each layer.
3K weave carbon fiber is the most widely recognized. In order to maintain the proper balance of carbon fiber and resin, we frequently include a 3K layer within the rim channel to eliminate excess resin. Additionally, the presence of small spaces within the 3K layer helps minimize the likelihood of imperfections on the rim’s surface. Furthermore, the 3K weave serves to safeguard the spoke hole from damage during the drilling procedure.
The 12K has a higher stiffness compared to the 3K. The wider weave has lower production costs, making the 12K layer slightly cheaper than the 3K.
In conclusion
In simple terms, the distinction is primarily focused on appearance rather than functionality. You are free to select the weave that appeals to you.
