Halfords 13 2014 User Manual page 39

Fatigue is not a Perfectly
Predictable Science
Fatigue is not a perfectly predictable science, but here are some general factors to help you
and your local 13 dealer determine how often your bicycle should be inspected. The more you
fit the "shorten product life" profile, the more frequent your need to inspect. The more you fit the
"lengthen product life" profile, the less frequently you will need to inspect.
Factors that shorten product life:
• Hard, harsh riding style
• "Hits," crashes, jumps, other shocks to bike
• High mileage
• Higher body weight
• Stronger, more fit, more aggressive rider
• Corrosive environment (wet, salt air, winter
road salt, accumulated sweat)
• Presence of abrasive mud, dirt, sand,
soil in the riding environment
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 fibres are strong and light, but when crashed or overloaded, carbon fibres 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 fibre bike." This really means "composite bike."
Carbon fibre composites are typically a strong, light fibre in a matrix of resin, moulded to form a
shape. Carbon composites are light relative to metals. Steel weighs 7.8 grams/cm
cubic centimeter), titanium 4.5 grams/cm
with carbon fibre composite at 1.45 grams/cm
The composites with the best strength-to-weight ratios are made of carbon fibre in a matrix of
epoxy resin. The epoxy matrix bonds the carbon fibres together, transfers load to other fibres,
and provides a smooth outer surface. The carbon fibres 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 fibres can be placed in specific orientations to optimize the structure for particular loads.
The choice of where to place the carbon fibres gives engineers a powerful tool to create strong,
light bicycles. Engineers may also orient fibres to suit other goals such as comfort and
vibration damping.
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Factors that lengthen product life:
• Smooth, fluid riding style
• No "hits," crashes, jumps, other shocks to bike
• Low mileage
• Lower body weight
• Less aggressive rider
• Non-corrosive environment (dry, salt-free air)
• Clean riding environment
3 , aluminium 2.75 grams/cm
.
3
Ask your local 13 dealer
3 (grams per
3 . Contrast these numbers
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