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PART 2
1. Understanding Metals
138692 Rev 0 (04/22)
Section D. Inspect For Safety
GT Bicycle Owner’s Manual
Aircraft, race cars, motorcycles: all have parts
with finite fatigue lives. If you wanted a bicycle
with an infinite fatigue life, it would weigh far
more than any bicycle sold today. So we all make
a trade-off: the wonderful, lightweight
performance we want requires that we inspect
the structure.
In most cases a fatigue crack is not a defect. It is
a sign that the part has been worn out, a sign the
part has reached the end of its useful life. When
your car tires wear down to the point that the
tread bars are contacting the road, those tires
are not defective. Those tires are worn out and
the tread bar says “time for replacement.” When
a metal part shows a fatigue crack, it is worn
out. The crack says “time for replacement.”
THIS IS A
BENT
METAL FORK.
THIS IS A
COMPLETELY BROKEN
CARBON FORK.
FIGURE A
