Here at Appleman Bicycles, strength and durability are a priority. That’s why I use unidirectional carbon fibers to build all of my frames. Many bikes have a cosmetic woven outer layer, but it is just that… cosmetic.
Unidirectional (UD) fibers are carbon fibers that run in one direction, similar to the grain of wood.
Woven fabrics have carbon fibers that run in two directions.
Carbon fibers are 70 times stronger with the “grain” than against it. When I design a carbon layup, I understand the forces applied to the frame and lay the carbon fiber to resist those forces. The angle of the fiber is critical. A layup must be designed with multiple angles and layers to resist different types of forces while riding.
UD fibers are the perfect tool to build a bike with because they are twice as strong and twice as stiff as woven carbon fibers! The weave of the fabric crimps the fibers and they are constantly bent in an “S” shape to go over and under each other. When force is applied to a woven fabric, the fibers bend and try to straighten out which reduces strength and stiffness. UD fibers lay flat and there is no flex when force is applied.
The result of flat, straight, UD fibers is a stronger, stiffer bike.