10
Shifting Gears
How a Derailleur Drive Train Works
Shifting Gears
Shifting the Rear Derailleur
Shifting the Front Derailleur
If your bicycle has a derailleur drive train,
gear-changing mechanisms include:
»» a rear cassette or free-wheel
sprocket cluster
»» A rear derailleur
»» in most cases, a front derailleur
»» 1 or 2 shifters
»» 1-3 front sprocket chainrings
»» a drive chain
There are several different types and
styles of shifting controls available:
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 how they work.
A downshift is a shift to a “lower” or “slower”
gear, which is easier to pedal. An upshift is
a shift to a“higher” or “faster” pedal gear.
To select a gear that will make pedalling
easier on a hill, you can change the downshift
gear 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 in the rear). A downshift moves
the chain up to a larger gear. Remember
that shifting the chain towards the centerline
of the bike is for accelerating and climbing,
which is called a downshift. Moving the chain
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 in a forward-moving motion and is
under some tension.
The right shifter controls the rear derailleur.
The main function of the rear derailleur is to
move the drive chain from one gear sprocket
to the other. Smaller sprockets on the rear
wheel gear cluster produce higher gear ratios.
When pedalling in higher gears, it requires
greater amount of effort, but will take you a
further distance with each turn of the pedal
crank. The larger sprockets produce lower
gear ratios, which use less pedalling effort,
but propel you a shorter distance with each
spin. Two set screws or limit screws on the
rear derailleur body are designed to restrict
the travel of the rear derailleur. By tightening
the high-rear derailleur adjustment gear
screws, it will keep the chain from shifting off
the small (high) gear. This is located on the
rear axel. Also, by tightening the low-rear
derailleur adjustment gear screws, you will
notice that the chain will stop from shifting
off the large (low) gear into the rear wheel.
When moving the chain from a smaller
sprocket (in the gear cluster) to a larger
sprocket, it will result in a downshift. Moving
the chain from the smaller sprocket on the
chainrings to a larger sprocket will result in
an “upshift”. In order for the derailleur to
move the chain from one sprocket to another,
the rider must be pedalling forward.
The front derailleur, which is controlled
by
the left shifter, switches the chain between
the larger and smaller chainrings.
Shifting
the chain onto a smaller chainring makes
pedalling easier (a
downshift), while shifting
to a larger chainring makes pedalling harder
(an
upshift). Two adjustment screws are
located on the front derailleur. The
first one
is to limit the travel of the front derailleur for
the chain to be
shifted upwards towards the
larger, higher pedal gears. This will not allow
the chain to “overshift.” The second 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” by keeping the
chain from falling off the chain wheel and
onto the frame.
Your multi-speed bicycle will have a
derailleur drive train, an internal gear
hub drive train, or in some cases a
combination of the two drive trains.
NOTE:
A derailleur will only shift if you are
pedalling forward.
