Verso KC720-220, Руководство пользователя

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The Lifespan of Your Bicycle
& its Components
cont’d
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
3
(grams per cubic centimeter), titanium 4.5 grams/cm
3
, aluminum 2.75 grams/cm
3
. Contrast
these numbers with carbon fiber composite at 1.45 grams/cm
3
.
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.
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.
Wile fatigue life is an advantage of carbon fiber, you must still regularly inspect your car-
bon 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?
Lets say you hit a curb, ditch, rock, car, other cyclist or other object. At any speed above a
50