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Shifting Gears
Your multi-speed bicycle will have a derailleur
drive train, an internal gear hub drive train or, in
some special cases, a combination of the two.
How a Derailleur Drive Train Works
If your bicycle has a derailleur drive train, the
gear-changing mechanism will have:
»» A rear cassette or freewheel sprocket cluster.
»» A rear derailleur.
»» Usually a front derailleur.
»» One or two shifters.
»» One, two or three front sprockets called
chain rings.
»» A drive chain.
Shifting Gears
There are several different types and styles
of shifting controls: levers, twist grips, triggers,
combination shift/brake controls and push
buttons. Ask your dealer to explain the type of
shifting controls that are on your bike, and to
show you how they work.
A downshift is a shift to a "lower" or "slower"
gear, one that is easier to pedal. An upshift is
a shift to a "higher" or "faster", harder to pedal
gear. To select a gear that will make pedaling
easier on a hill, make a downshift in one of
two ways: shift the chain down (the gear
"steps" to a smaller gear at the front) or shift
the chain up (the gear "steps" to a larger
gear at the rear.) So, at the rear gear cluster,
what is called a downshift actually moves the
chain up to a larger gear. 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.
Shifting the Rear Derailleur
The right shifter controls the rear derailleur.
The function of the rear derailleur is to move
the drive chain from one gear sprocket to
another. The smaller sprockets on the rear
wheel 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. There are two set screws or
limit screws on the rear derailleur body that
limit the
travel of the rear derailleur. Tightening the
rear derailleur high gear adjustment screw
keeps the chain from shifting off the small
(high) gear that is on the rear axle. Tightening
the rear derailleur low gear adjustment screw
keeps the chain from shifting off the large (low)
gear into the rear wheel. Moving the chain
from a smaller sprocket of the gear cluster
to a larger sprocket results in a downshift.
Moving the chain from the smaller sprocket
on the chain rings to a larger sprocket results
in what is called an "upshift." In order for the
derailleur to move the chain from one sprocket
to another, the rider must be pedaling forward.
Shifting the Front Derailleur
The front derailleur, which is controlled by the
left shifter, shifts the chain between the larger
and smaller chain rings. Shifting the chain onto
a smaller chain ring makes pedaling easier
(a downshift). Shifting to a larger chain ring
makes pedaling harder (an upshift). There are
2 (two) adjustment screws on the front derailleur:
one is to limit the travel of the front derailleur so
that the chain can be shifted upwards towards
the larger, higher or harder to pedal gears but
will not allow the chain to "overshift." The other
screw limits the travel of the front derailleur
towards the smaller or easier-to-pedal chain -
wheel. By limiting travel, it prevents the chain
from "undershifting" and keeps the chain from
falling off the chainwheel onto the frame.
09
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