is there any difference in ride quality between a frame made with a 3k carbon weave and a frame with a 12k carbon weave. is one better than the other?

By all accounts of people in the know, the carbon weave is cosmetic and has no impact to how the frame performs.

is there any difference in ride quality between a frame made with a 3k carbon weave and a frame with a 12k carbon weave. is one better than the other?

Wouldn't that depend on tube wall thickness, tube shape, tube diameter, quality of build, and a bunch of other factors?

http://carb.com/s.nl/it.I/id.2/.f

All else being equal, a 3k frame will be stronger. All else is never equal and frame ride usually depends on constructions techniques and such. Also worth noting, 3k/12k weave often refers to the cosmetic layer, not the actual structural fibers.

The structural carbon just looks black. The "weave" is laid on last for cosmetic purposes. If you took a painted frame and stripped the paint off, you wouldn't see much of a weave at all.

From what I understand the bikes that look "carbon" are from a cosmetic outer layer. Some companies even leave this off to save weight. The C'dale Super Six is an example.

Yes, there is a difference if frames with a different weave have other differences such as different carbon fibers. E.g., compare Pedal Force frames with Motobecane/Bottecchia and 2008 Scattante. They are different.

Wouldn't that depend on tube wall thickness, tube shape, tube diameter, quality of build, and a bunch of other factors?

Nope. Not at all. It's entirely material dependent. I'm pretty sure that I saw a test somewhere that showed that a bike frame made from solid chromoly 1.5" bar has a lively, yet comfortable ride while all the CF bikes that frame was tested against caused traumatic tooth loss and several strangulated hemorrhoids. Unfortunately none of the CF bike tests were able to run to completion since all of the CF frames exploded well before the end of the tests.

The structural carbon just looks black. The "weave" is laid on last for cosmetic purposes. If you took a painted frame and stripped the paint off, you wouldn't see much of a weave at all.

This is true only in part. UD CF is black; however, a few CF frame makers have said that woven CF matte can be and is used as a structural component.

well what does 3k and 12k even mean? i think it has to do with the weave, but what do the numbers tell you?

This is true only in part. UD CF is black; however, a few CF frame makers have said that woven CF matte can be and is used as a structural component.

I'm just posting what I was told by a couple frame builders. I don't claim to have any carbon knowledge...

well what does 3k and 12k even mean? i think it has to do with the weave, but what do the numbers tell you?

A single carbon fiber is actually a bundle of many carbon filaments. One 3k fiber is a bundle of 3,000 filaments, one 6k fiber is a bundle of 6,000 filaments, and so on. The photo shows one carbon filament (lower left to upper right) compared to a human hair.

Obviously, a 3k fiber is smaller than a 6k or 12k fiber. You have to get fairly close to a part to recognize a weave made with 3k fibers, so it's used in making a weave for small parts. If you want the weave to be visible from further away on a frame or fork, you'd specify one made with 12k or larger fibers. These are only the cosmetic considerations. There are large strength and weight differences between the different size fibers as well.

Check out this website. I am not claiming everything they say is accurate but they appear to know much more about carbon layups than I do. There is also a good PDF file at the bottom with additional results.
http://www.corecomposites.com/feature.cfm