Electra Bicycle User Manual

Page 26

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 fibers are strong and light, but when crashed or

overloaded, carbon fibers 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 fiber bike.” This

really means “composite bike.”

Carbon fiber composites are typically a strong, light fiber in a matrix of plastic,

molded to form a shape. Carbon composites are light relative to metals. Steel

weighs 7.8 grams/cm

(grams per cubic centimeter), titanium 4.5 grams/cm

aluminum 2.75 grams/cm

. Contrast these numbers with carbon fiber composite

at 1.45 grams/cm

The composites with the best strength-to-weight ratios are made of carbon

fiber in a matrix of epoxy plastic. The epoxy 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 directions (engineers call

this isotropic), carbon fibers can be placed in specific orientations 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 carbon fiber bicycles and components have long

fatigue lives, usually better than their metal equivalents.

While fatigue life is an advantage of carbon fiber, you must still regularly

inspect your carbon fiber frame, fork, or components.

Carbon fiber 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 fiber or carbon fiber 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 significant 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 find the source

of any noise. It may not be a crack or delamination, but whatever is causing the

noise must be fixed 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 profile as outlined above. The more you fit

the “shorten product life” profile, the more you must question the use of super

light components. The more you fit the “lengthen product life” profile, the more