Knowledge

DARE Carbon Tech

Date posted: 02/15/2016 12:31

Dare worked closely with Toray to develop a Multi-ply Synthetic Hot-Melted Carbon Fiber Resin (HS-HMC prepreg), which is a new kind of prepreg carbon fiber that has an extremely low FAW (Fiber Areal Weight) (g/m2)

The DARE HS-HMC multi-ply sheet is 10g lighter than the traditional sheet even though it’s composed by 9 layers carbon fiber, 4 layers more than the traditional sheet. This is because each carbon layer of the DARE HS_HMC sheet is only half the thickness and weight of the traditional carbon layers. The reduced weight allows us to create a lay-up with carbon layers multiple different directions compared to the traditional sheets. The unique layup of DARE HS-HMC sheets allow us to make frames that are stiffer, have better anti-deformation properties, and are lighter weight.

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The graph above shows the many different types of carbon fiber available. Each corresponding number represents a different type of usage based on tensile modulus and tensile strength.  While the majority of bicycle companies use High Strength T-Model carbon fiber (blue and green areas), DARE frames are made using High-Modulus M-Model carbon fiber, (red area) which is primarily used in the aerospace industry.

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Tensile Modulus – The elastic properties of carbon fiber when stretched or compressed. Test method: The carbon fiber test specimen can be measured in a static position then deformed until it fails. Result: High M-model fibers are stiffer and more difficult to deform. For example, the stiffness of M46 is higher than M40 and the former is also more expensive than the later.

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Tensile Strength: The maximum amount of tensile stress that a structure can take before failure. Test method: The carbon fiber test specimen can be measured in a static position then stretched until it fails. Result: Normally a T700 carbon bike can handle 5000Mpa of force whereas T1000 can handle 6500Mpa. This means the higher T value can handle higher amounts of stretch stress.     Even though High Modulus M-Model carbon fibers are much more expensive than High Strength T-Model carbon fiber, they have much better anti-deformation properties. They are not only a very stiff material but also have a very long life span, just like the space shuttle. This is a huge advantage over other bike brands, which generally only use High Strength T-Model carbon fibers.

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The comparison of Stiffness and Strength Stiffness is the degree of a frame’s deformation when the frame is impacted by an external force, the lower the stiffness the bigger the deformation. Strength is the amount of impact force a frame can take before sustaining damage, the lower the strength the greater the damage. Choosing a higher strength fiber will make for a safer frame because it will not be easily damaged while riding. However, a strong frame does not mean a stiff frame. A stiff frame will reduce the ride quality of the frame but will increase in efficiency and performance, saving critical watts.   In order to combine both high strength with greater stiffness, DARE selected expensive fibers (T1000, M40 and M46) and wrapped them in in varying directions for different areas of the frame to optimize ride quality and frame stiffness. DARE’s frame production is not only focused on creating the lightest frame possible, but also a strong and stiff frame that optimizes ride quality, rider safety and optimum performance.