The main type of carbon fiber used for the manufacture of bicycle parts are normal tow (under 12000 fibers) carbon fiber, like T700, or commonly known as 3k, 12k weave, and UD(uni-direction) carbon fiber.

Bicycle components, especially carbon fiber frames and rims, are made of various grades of carbon fiber. The main feature is its tensile strength and tensile modulus. The tensile strength is the amount of force required to cause the fiber to break, and the tensile modulus is a measure of the stiffness of the carbon fiber.

The cost of carbon fiber increases as the tensile strength or tensile modulus increases. And for carbon fiber weaving also determines the cost of the material, with a larger woven prepreg (for example, 12k), the cost is lower, because the manufacturing cost is lower.

The carbon fiber layer (prepreg) has maximum strength only along the length of the fiber. This is why almost all internal prepregs use unidirectional carbon fiber when manufacturing carbon fiber rims and frames. But the insider basket chart is still different. For example, the directions are different (some are placed at 0 degrees, some are placed at 45 degrees, 90 degrees). This is very important for making carbon fiber rims and frames with good strength and performance. This is why the use of unidirectional fibers instead of woven carbon fibers (such as 3k, 12k) can create stronger frames and rims.

Therefore, the main purpose of woven carbon fiber is for appearance. But 3k woven carbon fiber has a mechanical advantage. Placing 3k braided carbon fiber around the hole area can prevent carbon fiber lamination when processing the hole.

For the weight difference, the woven fibers have some areas that cross each other. Therefore, woven fibers are heavier than UD fibers. However, for the rim, the size of carbon fiber is not large, only one layer is different, and the weight of woven fiber (3k & 12k) and UD fiber is not much different. In addition, all rims have a weight range, for rims, it is +/-15g. Therefore, sometimes, 3k rims and frames are lighter than UD.

For big size product (like frame), 3k frame will be heavier than UD. And for 12k, the weight different is not much difference.