Operation Manual

45
WARNING: Do not ride a bicycle or component with any crack, bulge
or dent, even a small one. Riding a cracked frame, fork or component
could lead to complete failure, with risk of serious injury or death.
B. Understanding composites
All riders must understand a fundamental reality of composites. Composite
materials constructed of carbon bers are strong and light, but when crashed or
overloaded, carbon bers do not bend, they break.
What Are Composites?
The term “composites” refers to the fact that a part or parts are made up of
different components or materials. You’ve heard the term “carbon ber bike.” This
really means “composite bike.”
Carbon ber composites are typically a strong, light ber in a matrix of plastic,
molded to form a shape. Carbon composites are light relative to metals. Steel
weighs 7.8 grams/cm
3
(grams per cubic centimeter), titanium 4.5 grams/cm
3
,
aluminum 2.75 grams/cm
3
. Contrast these numbers with carbon ber composite
at 1.45 grams/cm
3
.
The composites with the best strength-to-weight ratios are made of carbon
ber in a matrix of epoxy plastic. The epoxy matrix bonds the carbon bers
together, transfers load to other bers, and provides a smooth outer surface. The
carbon bers are the “skeleton” that carries the load.
Why Are Composites Used?
Unlike metals, which have uniform properties in all directions (engineers call
this isotropic), carbon bers can be placed in specic orientations to optimize
the structure for particular loads. The choice of where to place the carbon bers
gives engineers a powerful tool to create strong, light bicycles. Engineers may
also orient bers to suit other goals such as comfort and vibration damping.
Carbon ber composites are very corrosion resistant, much more so than most
metals.
Think about carbon ber or berglass boats.
Carbon ber materials have a very high strength-to-weight ratio.
What Are The Limits Of Composites?
Well designed “composite” or carbon ber bicycles and components have long
fatigue lives, usually better than their metal equivalents.
While fatigue life is an advantage of carbon ber, you must still regularly
inspect your carbon ber frame, fork, or components.
Carbon ber composites are not ductile. Once a carbon structure is
overloaded, it will not bend; it will break. At and near the break, there will be
rough, sharp edges and maybe delamination of carbon ber or carbon ber fabric
layers. There will be no bending, buckling, or stretching.
IfYouHitSomethingOrHaveACrash,WhatCanYouExpectFromYour
Carbon Fiber Bike?
Let’s say you hit a curb, ditch, rock, car, other cyclist or other object. At
any speed above a fast walk, your body will continue to move forward, the
momentum carrying you over the front of the bike. You cannot and will not