Tubular Wheels

[Christie]

Im not a material expert, but this is how I have it:

3k=3000 fibers per bundle, 12k=12000 fibers per bundle. The 12k bundle is bigger than the 3k, so does not have more fibre density, just bigger blocks - 12 weave "squares" are visibly bigger.

 

12k rose to prominence when the aerospace industry, particularly new projects from Boeing & Airbus started putting strain on the supply of 3k. 3k became very expensive, as demand grew. The bike industry does not necessarily need the properties of 3k, so some manufacturers switched to 12k.

 

12k used to be very difficult to cut & lay up, but those problems have been mostly solved. As far as I know, 3k is still preferred in aerospace for structural components, for the same grade fiber and resin, I would think primarily based on impact and fatigue properties.

[Old school]

Buying carbon fibre products<?: prefix = o ns = "urn:schemas-microsoft-com:office:office" />

 

THE IMPORTANCE OF EPOXY RESIN

Before you buy, ask your seller: "What kind of resin does your company use for carbon fiber and its derivatives?"

The wrong answer is POLYESTER RESIN!!!

Polyester resin is the cheapest product that any company can buy when working with carbon fiber or its derivatives.

1.      Polyester resin has a blueish finish instead of a clear finish. The blue tint significantly reduces the appearance of the product.

2.      Polyester resin is inflexible and will spider-crack at the mere thought of bending. Spider cracks fracture from the point of damage and are very difficult to fix.

3.      Excessive amounts of polyester resin need to be used during the molding process. This adds considerable weight to the product and defeats the purpose of purchasing lightweight carbon fiber.

4.      Polyester resin will shrink over time and alter the shape of the final product, resulting in installation headaches and additional modifications for fit.

5.      Polyester resin is not UV resistant and will turn yellow over time.

The correct answer is EPOXY RESIN!!!

Epoxy resin is the industry standard for high-performance race products.

1.      Epoxy resin is extremely flexible. The flexibility allows a carbon fiber product to absorb a high level of impact force without breaking.

2.      Epoxy resin does not spider-crack. When epoxy reaches it?s maximum bending potential (MBP), it will form only a single crack at the stress point.

3.      Epoxy resin has a transparent finish that allows the deep, black 3D appearance of the carbon fiber to show through.

4.      Epoxy resin does not shrink.

5.      Epoxy is 100% UV resistant.

[swift]

Interesting stuff, thanks Christie and Mercx

[Johan Bornman]

Im not a material expert' date=' but this is how I have it:

3k=3000 fibers per bundle, 12k=12000 fibers per bundle. The 12k bundle is bigger than the 3k, so does not have more fibre density, just bigger blocks - 12 weave "squares" are visibly bigger.

 

12k rose to prominence when the aerospace industry, particularly new projects from Boeing & Airbus started putting strain on the supply of 3k. 3k became very expensive, as demand grew. The bike industry does not necessarily need the properties of 3k, so some manufacturers switched to 12k.

 

12k used to be very difficult to cut & lay up, but those problems have been mostly solved. As far as I know, 3k is still preferred in aerospace for structural components, for the same grade fiber and resin, I would think primarily based on impact and fatigue properties.

[/quote']

 

Question edited out. I see it has already been answered.

 

Johan Bornman2008-07-02 10:23:51

[swift]

Ok, those in the know say:

 

 

 

There is very little difference between 3K and 12K weave. The strength comes from the structural layers of carbon underneathe and the weave you can or can't see is mainly cosmetic.

[Christie]

There is very little difference between 3K and 12K weave.

Agreed. I would think for the same fiber and resin' date=' properties of the final product would depend mostly on fiber volume fraction (% fiber to % resin)The difference, if any, should be small. That said, even if fiber volume fractions were the same, 3k should have the better impact & fatigue properties, while 12k would offer a small bit higher stiffness at small displacements

 

The strength comes from the structural layers of carbon underneathe and the weave you can or can't see is mainly cosmetic.

Agree also. Could be uni directional/3k underneath, with 12k outer, or 12k underneath,  3k outer. Only way is to melt the resing with a heat gun, but this is best done with your broken or somebody else's components! 

[carlo_sg]

What do you notice about this picture....

 

... Clinchers. Kysrium SL, R-SYS, Cosmic Carbone SL

 

http://i290.photobucket.com/albums/ll253/carlo_sg/Tour08_1_Caduta3.jpg

[slowgo]

I did not know that