Shifting Gears - MARIN Bicycle Owner's Manual

A wheel with more weight on it will accept greater brake pressure before
lockup; a wheel with less weight will lock up with less brake pressure. So,
as you apply brakes and your weight is transferred forward, you need to
shift your body toward the rear of the bike, to transfer weight back on to the
rear wheel; and at the same time, you need to both decrease rear braking
and increase front braking force. This is even more important on descents,
because descents shift weight forward.
Two keys to effective speed control and safe stopping are controlling wheel
lockup and weight transfer. This weight transfer is even more pronounced
if your bike has a front suspension fork. Front suspension "dips" under
braking, increasing the weight transfer (see also Section 4.F). Practice
braking and weight transfer techniques where there is no traffic or other
hazards and distractions.
Everything changes when you ride on loose surfaces or in wet weather. It
will take longer to stop on loose surfaces or in wet weather. Tire adhesion
is reduced, so the wheels have less cornering and braking traction and can
lock up with less brake force. Moisture or dirt on the brake pads reduces
their ability to grip. The way to maintain control on loose or wet surfaces is
to go more slowly.
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
28
• 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.
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.
e. What if it won't shift gears?
If moving the shift control one click repeatedly fails to result in a smooth shift
to the next gear chances are that the mechanism is out of adjustment. Take
the bike to your dealer to have it adjusted.
2. How an internal gear hub drivetrain works
If your bicycle has an internal gear hub drivetrain, the gear changing
mechanism will consist of:
• a 3, 5, 7, 8, 12 speed or possibly an infinitely variable internal gear hub
• one, or sometimes two shifters
• one or two control cables
• one front sprocket called a chainring
• a drive chain
29