TENSILE STRENGTH ::
measures the force required
to pull a material apart. In
frame design, more tensile
strength means that less
material is needed, thereby
saving weight.
FATIGUE STRENGTH ::
measures how far and how
many times a material can
be flexed before it breaks.
Certain materials such as steel
and titanium can be tooled to
withstand an infinite number
of flexes without failure.
CORROSION RESISTANCE ::
Titanium is virtually
impervious to heat, cold,
fresh water, salt water, sweat,
ultraviolet light, infrared
light, and petroleum based
chemicals. This means low,
maintenance for the bicycle
frame.
DENSITY ::
The most important analysis
of density for cycling
applications is the material’s
density relative to its strength
and durability. Simply stated,
density is the weight of a
material for a given volume
such as pounds per cubic inch
or grams per cubic centimeter.
Titanium actually weighs the
most of the 3 primary frame
materials in this evaluation, at
.160 lb/sq.in., with Aluminum
at .098 lb/sq.in., and Carbonfiber
at .065 lb/sq.in.
Titanium’s unique strengthto-
weight ratio, allows us to
use less material for a lighter
weight tube.
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YIELD STRENGTH ::
measures how much force it
takes to permanently bend
a material. As with tensile
and fatigue strength, more is
better. The very high strength
levels of titanium again allow
less material to be used, which
saves weight.
ELONGATION ::
refers to the percentage a
material will stretch before
tearing or cracking. Ideally,
you want a material that will
give slightly before failure,
thus providing a safety factor.
TOUGHNESS ::
refers to how much a material
can deform or be damaged
before failure. The near
mythical toughness-to-weight
of titanium is why it is so often
used in military armor. On the
other hand, aluminum is an
extremely tough raw material,
but manufacturing lowers the
fatigue strength dramatically.
Carbon fiber has virtually
no resiliency once it is
dented or over-flexed, so
catastrophic failure can
result from what might seem
to be minor damage.
Careful consideration of each
of these factors is critical when
designing a high-performance
bike frame, because the TRUE
performance is the result of
how ALL these factors work
together. |
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