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  1. #1
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    Chinese carbon. 3k or ud?

    Wich is better?

  2. #2
    www.derbyrims.com
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    UD, less resin per volume. UD failures are rarely posted, probably because of rare failures. All the major brand rims appear to be UD, also with rare failures reported. Unlike monotone UD, the 3K is stylish, which may be better for some conditions too ; )

  3. #3
    Maromero
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    UD is supposed to be "stronger", anyway this is what Light-bicycle said:
    "For different weave, the strength and weight is almost the same. Because for rims, all the inside layers are the same, only the outer layer is different to make different outlook."
    I got the 3k, took 9 days to get here in Mex from China, not bad at all. Weight was 360.3 and 361.3 gr.

  4. #4
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    Ok thanks. I was actually thinking of the frame. But still very helpful

  5. #5
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    The latest thoughts on this as per the NOX Composites website is that the 3k weave is better because it is not as brittle as the UD. It will displace some of the pressure because it is not as hard. Think of it as helicopter tape protection.....Personally I would not take anything LB says. They are merely a Trading Company......

  6. #6
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    To clarify, it depends on the application. We like to use the analogy of a long piece of wood like a 2X4. Think of this piece of wood like a large bundle of UD fibers (called a tow) all aligned the same way. This creates a very strong structure (In certain directions, but let's ignore that for now) BUT, if you drill a large hole in the middle, then you have compromised the strength of the entire structure because you've cut/drilled almost all the fibers. Counter to this is weave fabric, if you have the same 2X4 structure made of weaved fabric, then drilling a hole in the middle would not weaken the 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) fibers. Now, this doesn't mean 3K is always better, because in general with a bicycle frame or rim, UD will give you the most strength for the weight and allow the engineer more control in the layup patterns to optimize the structure. However, you want to avoid drilling it as much as possible. This is the reason you'll see 3K fabric supporting all the drill holes in our rims while the majority of the rim itself is made of UD fiber.

    I'd be weary of anyone that claims the difference is only cosmetic.
    Nox Composites
    Carbon Fiber Mountain Rims and Wheels

  7. #7
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    I would substitute the word drill with scratch or impact.....it does not have to be a hole to start the process....

  8. #8
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    ud stand for uni-directional right? ply wood wood be the correct analogy. the grain of the wood in each layer is not running in the same direction. for structural integrity each layer is perpendicular from the one next to it. or the opposite of parallel if perpendicular isn't the right word. better yet the opposite of uni-directional. lol

  9. #9
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    Yes, plywood is a good analog for how UD carbon structures are built. The engineering is in the "layup" which is the angle of each layer relative to the others such that you achieve optimum weight and strength and in the case of frames, elasticity.

    But a full layup is not what I was referring to in my message above. I was keeping it simple and considering one tow (i.e. one layer of ply wood) for the sake of illustrating the strengths/weakness of UD versus 3K.
    Nox Composites
    Carbon Fiber Mountain Rims and Wheels

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