34
Tech
Shifting gears
35) or, in some special cases, a combi-
nation of the two.
How a derailleur drivetrain
works
If your bicycle has a derailleur drivetrain,
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
chainrings
A drive chain
Shifting Gears
There are several different types and
styles of shifting controls: levers, twist
grips, triggers, combination shift/brake con-
trols 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.
The vocabulary of shifting can be pretty
confusing. A downshift is a shift to a “lower”
or “slower” gear, one which is easier to
pedal. An upshift is a shift to a “higher” or
“faster”, harder to pedal gear. What’s con-
fusing is that what’s happening at the front
derailleur is the opposite of what’s happen-
ing at the rear derailleur (for details, read the
instructions on Shifting the Rear Derailleur
and Shifting the Front Derailleur below).
For example, you can select a gear which
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 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.
Never move the shifter while pedaling
backward, nor pedal backwards immedi-
ately after having moved the shifter. This
could jam the chain and cause serious
damage to the bicycle.
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 sprock-
ets 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 pro-
duce 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 derail-
