As we covered in Physics of 3D Printing, imagine the fiber is like raw spaghetti. If you try to bend it, it snaps. If you try to compress it lengthwise by trying to push the two endpoints closer together, it also snaps. However, if you load it in tension by pulling on it, it can hold a decent load. Like the spaghetti, continuous fibers are strongest when loaded in tension. The key is understanding where the fibers are loaded in tension, and how a given load can distribute amongst the local fibers.