Is there a performance difference? Weight? Quality?
Allan, I think it means fibres per square inch if i remember correctly. A 12 k weave will have four times as many as a 3 k, but probably finer fibres.
Something also to do with high density modulus vs low density. Don’t assume the high density is always better however. Apparently it’s stiffer but more brittle. The lower density provides a more compliant ride. So it depends on the application it’s used for.
Hopeful one of the industry people or materials engineers will explain this better.
I think it’s just a cosmetic application to the very top layer in many cases.
these are designations for how many individual carbon fiber filaments are within each larger strand (or, in the biz parlance, in each “tow”). 3000 and 12000 filaments/tow, respectively. for a given grade/type/modulus of fiber, any strength-related performance difference is related solely to the larger filament count. the tradeoff tends to be decreased manufacturability with 12k tows where smaller parts or tighter angles are concerned. while this can be overcome by flattening out the larger tows to get a thinner, more pliable broadgood, all you really accomplish is to get back to where you were with the smaller tows with respect to load capability at the same ply thickness. that and a distinctive (and therefore marketable) look, if you’re using 12k woven stuff.
so, no performance or quality difference (for the same fiber), and no weight difference if you’re using 3k- or 12k-based broadgoods at the same per-ply thickness.
Carl
Thanks for the info. I’ve just seen info where they say “uses 12k carbon … blah blah” and wondered if this was a selling feature (other than the heavy duty checkerboard look) that meant something.
when you talk about smaller parts or tighter angles, is this more of a factor in monocoque frames than in lugged ones?
Actually, The prevelance of 12K woven materials was brought about due to two factors: Cosmetics (something different), and more importantly, availability. 3K materials have been in short supply at times due to military and aerospace application usage.
No weight or performance difference really as it is cosmetic. Kind of like black paint versus white paint.
Herbert
where hand-laid carbon parts are concerned, it’s mostly a function of geometry rather than frame assembly style. forming broadgoods over/into contours and into/over tight radii while maintaining laminate quality runs up against certain limits. it’s a challenge that every company addresses in their own way.
Carl
No weight or performance difference really as it is cosmetic. Kind of like black pain versus white paint.
Come on now Herbert, everyone knows that white paint is heavier than white paint…that’s why all the P3C’s are black 
Is there a performance difference? Weight? Quality? **well the 3k if you take the same stiffness from the fibers is stiffer **
**this because the crossings are smaller there for more straight **
12 k is easier to make hence you only need 1 layers in stead of 3 layers so less work too and cheaper
down side is that high modulus fibers are not avaible in 3k versions , if they make the same weight of the bike in 3 and 12 k they using low modular fibers probely they 5 times cheaper then high modules fibers
and there even 1k fibers that people think as top of the bill ,but the case is its expensive and low modules fibers more for finishing surface and most compagnys cannot even calc the stress inside a weave so…
well most of the time its marketing ,hence its all black
and in the world of blind one eye is king ****
Is there a performance difference? Weight? Quality?
A good marketing department.