TEN THINGS YOU NEED TO KNOW ABOUT CARBON FIBER
(1) Weight versus strength. Carbon fiber is the lightest and strongest per weight material known. It is one-half the weight of aluminum with three times the strength. Carbon fiber is extremely versatile and well suited for applications where stiffness and low weight are required. Carbon fiber allows a designer virtually unlimited ability to build parts with stiffness and strength that far exceeds aluminum, steel, and even titanium.
(2) CTE. The parts can be tailored to have strength and stiffness in the directions and locations the designer deems necessary, making it relatively easy to form complex, integrated structures with a superior overall shape and value. Carbon fibers by themselves have a negative coefficient of thermal expansion (CTE)—meaning that when they are heated, they shrink. Even when the fibers are put into a resin matrix, the composite can be tailored to have almost zero CTE. Carbon’s thermal stability increases manufacturing precision. Aluminum, steel and titanium all increase in size when heated.
(3) The matrix. Carbon fiber composite products are made by combining reinforcement (fiber) with matrix (resin). This combination of the fiber and matrix gives characteristics superior to either of the materials alone. In a composite material, the fibers carry the majority of the loads and characterize the material’s properties. The resin helps to transfer loads between fibers, prevents the fibers from buckling, and binds the materials together. Anything made of carbon fiber is loosely called carbon or carbon composite.
(4) Vinylester. The most common resins used to bind carbon are polyester, vinylester or epoxy. All have different levels of strength, durability, hardness and flexibility. Lightspeed uses epoxy resin, which is best known for its strength and durability.
(5) Ground down. Graphite carbon, also called thermal carbon, is a “grind” of carbon fibers that are mixed with resin and injection formed at extreme heat and pressure. It can be thought of as a heat-treated carbon fiber. Some mountain bike handlebars, which need to be extremely strong and lightweight, are produced using a thermal plastic carbon process. It is also used to construct tennis rackets, snow shoes, mountain bike frames and Formula One and jumbo jet disc brake rotors.
(6) 2×1 twill. Injection molded carbon doesn’t have long continuous fiber strands that are woven together. Its varying, mixed finish doesn’t give the aesthetic value of carbon parts with the weave. Weave patterns of carbon fibers can be oriented to allow for different directional strength, torsional stiffness, lateral rigidity, and other specific mechanical properties. Lightspeed uses the popular 2×2 twill 3K CF weave. The “2×2” is the fiber over-under cross weave, the “Twill” is the pattern, the “3” is the carbon fiber strand count per cross pattern, times the “K” (one thousand). So a 3K weave is 3000 strands of fibers per cross pattern.
(7) Orientation. The engineer can choose from a wide variety of fibers and resins to obtain the desired material properties. Also, the material thickness and fiber orientations can be optimized for each application. The use of woven Kevlar, commonly known for its bulletproof applications, increases the sheer tensile strength of carbon fiber. As soon as Kevlar or any other material is added, carbon fiber becomes a carbon composite. LightSpeed strategically places Kevlar on selected components for increased durability.
(8) Components. In the mid 1990’s, Team Kawasaki was the first motocross company to experiment with carbon fiber on their bikes. Later, the material was put to great use in the design of Doug Henry’s 1997 YZ400F factory bike. Skid plates, case guards, frame guard, chain guides, disc guards, fork guards, pipe hangers, mufflers, brackets, ignition covers, clutch covers, sprocket covers, case savers, tank covers, pinch clamps, helmets, knee and wrist braces and neck braces are all made from carbon fiber. Other carbon fiber components for motocross bikes are used to achieve cooler operating temperatures. Items such as heat shields, air tracts, rear caliper brake ducts, gas tank undertrays and so on.
(9) Price. Cost and weight are still the primary limiters of the wide use of carbon composite material on motocross bikes. Currently, the only parts that the AMA rule book disallows are carbon fiber disc brake rotors, number plates and disc brake parts.
(10) Lifespan. Over time carbon fiber has a tendency to age and dry out. This can be lessened with a few precautions. After washing your motorcycle, apply some kind of protectant or silicone to restore carbon fiber’s shiny appearance. The best thing to use on your carbon fiber parts is Maxima SC1. Be careful not to get any on the brake rotors. You can always apply it to a cloth first and then use the treated cloth to wipe the carbon fiber.