The composite s with th e best strength-to- weight ratios ar e made of carb on fiber in a ma trix of ep oxy plastic. The epo xy
matrix bonds the carbon fibers together, transfers load to other fibers, and provides a smooth outer surface. The carbon fibers are
the “skeleton” that carries the load.
Why Are Composites Used?
Unlike metals, which have uniform properties in all dir ections (engineers call this isotro pic), carbon fiber s can be pl aced in
specific or
ienta
tions to optimize the structure for particular loads. The choice of where to place the carbon fibers gives engineers
a powerful tool to create strong, light bicycles. Engineers may also orient fibers to suit other goals such as comfort and vibration
damping.
Carbon fiber composites are very corrosion resistant, much more so than most metals.
Think about carbon fiber or fiberglass boats. Carbon fiber materials have
a very high strength-to-weight ratio.
What Are The Limits Of Composites?
Well designed “composite” or carbo n fiber bi cycles and components have long fatig
ue lives, usually better than their metal
equivalents.
While fati gue life is an a dvantage of car bon fi ber, you must still re gularly inspect your car bon fi ber frame, for k, or
components.
Carbon fiber composites are not ductile. Once a carb on structure is overload
ed, it will not bend; it will break. At and near
the break, there will be rough, sharp edges and maybe delamination of carbon fiber or carbon fiber fabric layers. There will be no
bending, buckling, or stretching.
If You Hit Something Or Have A Crash, What Can Y
ou Expect From Your Carbon Fiber Bike?
Let’s say you hit a curb, ditch, rock, car, other cyclist or other object. At an
y speed above a fast walk, your body will continue
to move for ward, the mome ntum carr ying you ov er the fr ont of the b ike. You can not a nd will n ot st ay o n the bike and what
happens to the frame, fork and other components is irrelevant to what happens to your body.
What should you expect from your carbon frame? It depends on many complex factors. But
we can tell you that if the impact
is hard e nough, the fork or frame ma y be completely bro ken. Note the significant dif ference i n beh avior bet ween ca rbon a nd
metal. See Section 2. A, Understanding metals in this Appendix. Even if the carbon frame was twice as strong as a metal frame,
once the carbon frame is overloaded it will not bend, it will break completely.
Inspection of Composite Frame, Fork, and Components Cracks:
Inspect for cracks, broken, or splintered areas. Any crack is serious.
Do not ride any bicycle or component that has a crack of
any size. Delamination: Delamination is serious damage. Composites are made from la yers of fabric. Delamination means that
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