Electra Bicycle - 5. Service and Maintenance; Service Complexity and Dealer Reliance

46
47
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
stay on 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 enough, the fork
or frame may be completely broken. Note the signicant difference in behavior
between carbon and 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 layers of
fabric. Delamination means that the layers of fabric are no longer bonded
together. Do not ride any bicycle or component that has any delamination.
These are some delamination clues:
1. • A cloudy or white area. This kind of area looks different from the ordinary
undamaged areas. Undamaged areas will look glassy, shiny, or “deep,” as if one
was looking into a clear liquid. Delaminated areas will look opaque and cloudy.
2. • Bulging or deformed shape. If delamination occurs, the surface shape may
change. The surface may have a bump, a bulge, soft spot, or not be smooth and
fair.
3. • A difference in sound when tapping the surface. If you gently tap the surface
of an undamaged composite you will hear a consistent sound, usually a hard,
sharp sound. If you then tap a delaminated area, you will hear a different sound,
usually duller, less sharp.
Unusual Noises:
Either a crack or delamination can cause creaking noises while riding. Think
about such a noise as a serious warning signal. A well maintained bicycle will
be very quiet and free of creaks and squeaks. Investigate and nd the source
of any noise. It may not be a crack or delamination, but whatever is causing the
noise must be xed before riding.
WARNING: Do not ride a bicycle or component with any
delamination or crack. Riding a delaminated or cracked frame, fork
or other component could lead to complete failure, with risk of
serious injury or death.
C. Understanding components
It is often necessary to remove and disassemble components in order to
properly and carefully inspect them. This is a job for a professional bicycle
mechanic with the special tools, skills and experience to inspect and service
today’s high-tech high-performance bicycles and their components.
Aftermarket “Super Light” components
Think carefully about your rider prole as outlined above. The more you t
the “shorten product life” prole, the more you must question the use of super
light components. The more you t the “lengthen product life” prole, the more