About our Spokes
While Mad Fiber spokes do the same basic work as metal spokes, they do it in a very different way. Some unique characteristics:
Our spokes are made of 5 carbon plies. The outer two can be seen, a 12K weave oriented 0-90º on front and rear non-drive spokes, and 45º on rear drive side (crossed) spokes. Inside are three plies of unidirectional cloth, in which all fibers are at nearly 0º, directly aligned with spoke tension. These sturdy ribbons are more than 40 times stronger than the tensile loads they will see in our wheels.
The spokes are flat ribbons for several reasons. First, this affords them plenty of bonding area at the hub and rim. At the hub, for example, each has about 3/4 sq in of bond area. Our aerospace adhesive is rated at 6,000psi shear strength. That calculates to a load capacity of 4,500lbs. Certainly, we don't enjoy all of that in our structure, but the spoke tension (always below 200lb) is easily supported by this system, guaranteeing that the bond will never experience fatigue.
Thin, ribbon spokes make for sleek aerodynamics. Ours are about 0.7mm thick.
They are also flexible, which is useful because, absent tension, carbon is not an exceptional compression load carrier. If our spokes are momentarily compressed, they simply bend and return like a steel spoke. Flexibility also means our spoke cannot maintain its direction if it strikes something. Our testing shows that anything caught in the wheel will twist our spokes 90degrees, which they are capable of doing without damage. This means that the force is generally absorbed against a broad surface, rather than on the leading edge of the spoke.
NEXT: Aerodynamics
