It is important to inspect your bike before every ride using the
Mechanical Safety Check outlined in Section 1. C of this manual.
Additionally, periodic detailed inspections are necessary, and the
frequency depends on your usage. As the rider/owner, you have
control and knowledge of how often and how intensely you use
your bike and where you ride it. Your dealer can not track your
use, so it is your responsibility to bring your bike to them periodi-
cally for inspection and service. Your dealer can recommend the
appropriate frequency based on your usage.
WARNING
A. UNDERSTANDING METALS:
Steel has long been the traditional choice for building bicycle frames
due to its favorable characteristics. However, in high-performance
bicycles, aluminum and titanium have largely replaced steel. This
shift is driven by the desire of cycling enthusiasts for lighter bicycles.
When considering the use of different metals for bicycles, it is
important to understand that their suitability cannot be simplified
into a single statement. The application of the metal, including the
design, testing, and manufacturing process, along with the specific
characteristics of the metal, are more significant considerations than
the material itself.
Metals vary widely in their resistance to corrosion. Steel, for example,
requires protection from rust, which can corrode it. On the other
hand, aluminum and titanium quickly develop a protective oxide
layer that prevents further corrosion. While both aluminum and
titanium are highly resistant to corrosion, aluminum may still be
susceptible to galvanic corrosion when in contact with other metals.
Metals exhibit different levels of ductility, which refers to their ability
to bend, buckle, and stretch before breaking. Among common
bicycle frame materials, steel is the most ductile, followed by
titanium and then aluminum.
Metals also vary in density, which is a measure of weight per unit of
material. Steel has a density of 7.8 grams/cm3, titanium has a density
of 4.5 grams/cm3, and aluminum has a density of 2.75 grams/cm3. In
contrast, carbon fiber composite materials have a much lower
density of 1.45 grams/cm3.
One important aspect to consider when using metals in bicycles is
fatigue. Over time, metals can develop cracks due to repeated loading,
which can eventually lead to failure. Understanding the basics of metal
fatigue and the contributing factors is crucial.
Fatigue damage occurs on a microscopic level, with cracks forming in
highly stressed areas. As the load is repeatedly applied, these cracks grow.
Eventually, they become visible and large enough to weaken the part,
making it unable to carry the load it previously could. This can result in a
sudden and complete failure of the part.
While it is possible to design a part with an almost infinite fatigue life,
achieving this requires a significant amount of material and weight. Any
structure that needs to be lightweight and strong will inherently have a
finite fatigue life. Therefore, trade-offs must be made to prioritize desired
lightweight performance while also ensuring regular inspections of the
structure for potential issues.
In summary, the choice of metal for a bicycle frame involves various
complex factors, and crashworthiness cannot be determined solely based
on the material. Factors such as impact force and specific loading
conditions can result in bending, buckling, or even separation of parts.
Regular inspections and maintenance are essential to ensure the
longevity and safety of your bike.
What to look for
ONCE CRACKS BEGIN, THEY CAN
EXPAND RAPIDLY:
Consider cracks as pathways to failure. Any crack,
regardless of size, has the potential to be dangerous
and will only become more so over time.
SIMPLE RULE 1
If you discover a crack,
replace the affected part.
SIMPLE RULE 2
Maintain a clean bike,
regularly lubricate it, protect
it from salt, and promptly
remove any salt buildup.
SIMPLE RULE 3:
Avoid scratching, gouging,
or scoring any surface. If you
unintentionally cause
damage, closely monitor
that area or replace the part
if necessary.
ONCE CRACKS BEGIN, THEY CAN
EXPAND RAPIDLY:
Cracks tend to grow faster in corrosive
environments. Visualize corrosion as further
weakening and extending the crack.
SIGNIFICANT SCRATCHES, GOUGES, DENTS,
OR SCORING CREATE VULNERABLE POINTS
FOR CRACKS:
Imagine a surface that has undergone damage as a
focal point for stress. Engineers often refer to such
areas as stress risers, where stress is intensified. You
may have observed how scoring glass can lead to it
breaking along the scored line.
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