Toray is a reputable manufacturer of carbon fiber. We import the carbon materials directly from Japan and manufacture the bicycle rims with full carbon Toray T700.
Carbon has a lot of different appearances. The most common ones are UD, 3k and 12k.
UD/3k/12k specify the carbon weave pattern. UD carbon(Uni-Directional) has fibers that run the same way rather than being woven together. 3K means there are 3,000 filaments per "tow". 12K means there are 12,000 filaments per "tow".
Currently, UD and 3k weave are more and more popular, but the difference is not only cosmetic.
Most of customers are confused which weave is more stronger. It’s hard to tell which one will better. Each of weaves has a certain purpose.
The carbon fiber grade and orientation will affect the strength of carbon rim(eg. 0 degree, 45 degree, 90 degree). The layup method is a crucial factor for every company. UD weave(in certain direction) creates a very strong structure. BUT, if you drill a large hole in the middle of the rim, it has compromised the strength of the entire structure because you've cut/drilled almost all the fibers. For 3k, it’s OK to drill a hole in the middle which would not weaken the rim structure as much because your cut would have only severed a small portion of the total fibers and the drilled area is able to get support from it's neighboring (non-cut) carbon fibers. 3k weave is better because it is not as brittle as the UD. It displaces some of the pressure because it is not as hard as UD. However, this doesn't mean 3K is always better, because UD generally gives rim the most strength and allows the engineer more control in the layup patterns to optimize the rim structure. This is the reason we use 3K fabric to support all the drill holes in our rims while the majority of the rim itself is made of UD fiber. From the UD and 3k outlook rims, they are only last carbon layer difference and others are the same.
After rim sanding, we do matte or glossy finish to cover the rim. For the matte finish, the bicycle rim surface scratches(micro marring) may be not easy to see and it will help to hide imperfections in carbon layers. But it requires more maintenance to look clean because oils, sweat, and smudges may show more easily.
For the glossy finish, scratches can be buffed out. One of the virtues is that glossy finish will provide a “clear” barrier between the environment and your rim. Same riders prefer this kind of cool clear coating, because it looks very shiny and the effect is much like metallic, pearl, flip flop, etc. But the dirt and the scratches can be more visible