Jamis Bicycle - D. Shifting gears

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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 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. 16) is for the steepest hills.
The smallest rear and largest front combination 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 acceleration 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. Learn to anticipate the need to shift, and shift
to a lower gear before the hill gets too steep. If you have difficulties with shifting, the problem
could be mechanical adjustment. See your dealer for help.
WARNING: Never shift a derailleur onto the largest or the smallest sprocket if the
derailleur is not shifting smoothly. The derailleur may be out of adjustment and the
chain could jam, causing you to lose control and fall.
D. Shifting gears
Your multi-speed bicycle will have a derailleur drivetrain (see 1. below), an internal gear hub drivetrain (see 2. below) or, in some special cases, a
combination of the two.
1. 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
a. 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.
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 confusing is that what’s happening at the front derailleur is the opposite of what’s
happening 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.
CAUTION: Never move the shifter while pedaling backward, nor pedal backwards immediately after having moved the shifter.
This could jam the chain and cause serious damage to the bicycle.