tradeoff: the wonderful, lightweight performance we want requires that we inspect the structure.
What to look for
• ONCE A CRACKS ST ARTS IT CAN GR OW AND GR OW FAST. Think
abo
ut the crack as forming a
path- way to failure. This means that any crack
is potentially dangerous and will only become more dangerous.
SIMPLE RULE 1 : If you fin d crack, repl ace the
part.
• CORROSSION SPEEDS DAMAGE. Cracks grow more quickly when they
are in a corrosive environment. Think about the corrosive solution as further
weakening and extending the crack.
SIMPLE RULE 2 : Clean your bike, lubric ate your
bike, protect your b
ike from salt, remove any salt
as soon as you can.
• STAINS AN D DISCOLORA TION CAN OCCUR NEAR A CRACK. Such
staining may be a warning sign that a crack exists.
SIMPLE RUL E 3 : Inspect and investigate an y
staining to see if it is associated with a crack.
• SIGNIFICANT SCRATCHES, GOUGES, DENTS OR SCORING CREATE
STARTING POINTS FORCRACKS. Think about the cut surface as a focal
point for stress (in fact en gineers c all s uch are as “stres s ris- ers,” are as
where the stress is increase d). Perhap s you have se en g lass cut? Reca ll
how the glass was scored and then broke on the scored line.
SIMPLE RULE 4 : Do not scratch, gouge or score
any s
urface. If you do, pay fre- quent attentio n to
this area or replace the part.
• SOME CRACKS (particularly larger ones) MAY MAKE CREAKING NOISE
AS YOU RIDE. Think about such a noise as a serious warning signal. Note
that a well- m aintained bic ycle will be ver y quiet an d fre e of creaks an d
squeaks.
SIMPLE RUL E 5 : Investi- gate an d fin d the
source of a ny noise. It may not a be a crack , but
whatever is caus- ing the n oise shou ld be f ixed
promptly.
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 it s useful l ife. W hen your car tires wear down to the p oint that the tr ead bars ar e c ontacting the r oad, thos e tire s are n ot
defective. Those tires are worn out and the tread b ar says “time for replacement.” When a metal part shows a fatigue crack, it is
worn out. The crack says “time for replacement.”
Fatigue Is Not A Perfectly Pr edictable Sci ence Fatigue is not a perfectl y pre dictable s cience, but her e are some g eneral
factors to help you and your dealer determine how often your bicycle should be inspected. The more you fit the “shorten product
life” profile, the more frequent your ne ed to inspect. The more you fit the “lengthen product life” profile, the less frequent your
need to inspect.
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