
29
WARNING:
n
ever
inflate
a
tire
beyond
the
maximum
pressure
marked
on
the
tire
’
s
sidewall
. e
xCeeding
the
reCommended
maximum
pressure
may
blow
the
tire
off
the
rim
,
whiCh
Could
Cause
damage
to
the
bike
and
injury
to
the
rider
and
bystanders
.
The best and safest way to inflate a bicycle tire to the correct pressure is with a bicycle pump
which has an accurate built-in pressure gauge.
WARNING:
t
here
is
a
safety
risk
in
using
gas
station
air
hoses
or
other
air
Compressors
. t
hey
are
not
made
for
biCyCle
tires
. t
hey
move
a
large
volume
of
air
very
rapidly
,
and
will
raise
the
pressure
in
your
tire
very
rapidly
,
whiCh
Could
Cause
the
tube
to
explode
.
Tire pressure is given either as maximum pressure or as a
pressure range. How a tire performs under different terrain or
weather conditions depends largely on tire pressure. Inflating
the tire to near its maximum recommended pressure gives the
lowest rolling resistance; but also produces the harshest ride.
High pressures work best on smooth, dry pavement.
Very low pressures, at the bottom of the recommended
pressure range, give the best performance on smooth, slick
terrain such as hard-packed clay, and on deep, loose surfaces
such as deep, dry sand.
Tire pressure that is too low for your weight and the riding conditions can cause a puncture of the
tube by allowing the tire to deform sufficiently to pinch the inner tube between the rim and the
riding surface.
CAUTION:
p
enCil
type
automotive
tire
gauges
Can
be
inaCCurate
and
should
not
be
relied
upon
for
Consistent
,
aCCurate
pressure
readings
. i
nstead
,
use
a
high
quality
dial
gauge
.
Ask your dealer to recommend the best tire pressure for the kind of riding you will most often
do, and have the dealer inflate your tires to that pressure. Then, check inflation as described in
Section 1.C.3. so you’ll know how correctly inflated tires should look and feel when you don’t
have access to a gauge. Some tires may need to be brought up to pressure every week or two.
Some special high-performance tires have unidirectional treads: their tread pattern is designed
to work better in one direction than in the other. The sidewall marking of a unidirectional tire will
have an arrow showing the correct rotation direction. If your bike has unidirectional tires, be sure
that they are mounted to rotate in the correct direction.
2. Tire Valves
There are primarily two kinds of bicycle tube valves: The Schrader Valve and the
Presta Valve. The bicycle pump you use must have the fitting appropriate to the
valve stems on your bicycle.
The Schrader valve (fig. 18a) is like the valve on a car tire. To inflate a Schrader
valve tube, remove the valve cap and clamp the pump fitting onto the end of the
valve stem. To let air out of a Schrader valve, depress the pin in the end of the
valve stem with the end of a key or other appropriate object.
The Presta valve (fig. 18b) has a narrower diameter and is only found on bicycle
tires. To inflate a Presta valve tube using a Presta headed bicycle pump, remove
Summary of Contents for Bike
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