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at the front, or up the gear “steps” to a larger gear at the rear. So,
at the rear gear cluster, what is called a downshift looks like an
upshift. The way to keep things straight is to remember that shifting
the chain in towards the centerline of the bike is for accelerating
and climbing and is called a downshift. Moving the chain out or
away from the centerline of the bike is for speed and is called an
upshift.
Whether upshifting or downshifting, the bicycle derailleur
system design requires that the drive chain be moving forward and
be under at least some tension. A derailleur will shift only if you are
pedaling forward.
Caution: Never move the shifter while pedaling backward, nor pedal back-
wards after having moved the shifter. This could jam the chain and cause
serious damage to the bicycle and may cause you to lose control and fall.
b.
Shifting the Rear Derailleur
The rear derailleur is controlled by the right shifter. The function
of the rear derailleur is to move the drive chain from one gear
sprocket to another. The smaller sprockets on the gear cluster
produce higher gear ratios. Pedaling in the higher gears requires
greater pedaling effort, but takes you a greater distance with
each revolution of the pedal cranks. The larger sprockets produce
lower gear ratios. Using them requires less pedaling effort, but takes
you a shorter distance with each pedal crank revolution. Moving
the chain from a smaller sprocket of the gear cluster to a larger
sprocket results in a downshift. Moving the chain from a larger
sprocket to a smaller sprocket results in an upshift. In order for the
Fig. 21
!
derailleur to move the chain from one
sprocket to another, the rider must be
pedaling forward.
c.
Shifting the Front Derailleur:
The front derailleur, which is controlled by
the left shifter, shifts the chain between the
larger and smaller chainrings. Shifting the
chain onto a smaller chainring makes
pedaling easier (a downshift). Shifting to a
larger chainring makes pedaling harder
(an upshift).
d.
Which gear should I be in?
The combination of largest rear and
smallest front gears (fig. 21) is for the steepest
hills. The smallest rear and largest front combination
(fig. 21) is for the greatest speed. It is not necessary to shift gears in
sequence. Instead, find the “starting gear” which is right for your
level of ability — a gear which is hard enough for quick accelera-
tion but easy enough to let you start from a stop without wobbling
— and experiment with upshifting and downshifting to get a feel
for the different gear combinations. At first, practice shifting where
there are no obstacles, hazards or other traffic, until you’ve built up
your confidence. If you have difficulties with shifting, the problem
could be mechanical adjustment. See your dealer for help.
