22
23
WARNING: The full force of the cam action is needed to clamp the
seat post securely. Holding the nut with one hand and turning the
lever like a wing nut with the other hand until everything is as tight as
you can get it will not clamp the seat post safely.
WARNING: If you can fully close the cam lever without wrapping your
fingers around the seat post or a frame tube for leverage, and the
lever does not leave a clear imprint in the palm of your hand, the
tension is insufficient. Open the lever; turn the tension adjusting nut
clockwise a quarter turn; then try again.
C. Brakes
There are three general types of bicycle brakes: rim brakes, which operate by
squeezing the wheel rim between two brake pads; disc brakes, which operate
by squeezing a hub-mounted disc between two brake pads; and internal hub
brakes. All three can be operated by way of a handlebar mounted lever. On some
models of bicycle, the internal hub brake is operated by pedaling backwards.
This is called a Coaster Brake and is described in Appendix C.
WARNING:
1. Riding with improperly adjusted brakes, worn brake pads, or
wheels on which the rim wear mark is visible is dangerous and can
result in serious injury or death.
2. Applying brakes too hard or too suddenly can lock up a wheel, which
could cause you to lose control and fall. Sudden or excessive application
of the front brake may pitch the rider over the handlebars, which may result
in serious injury or death.
3. Some bicycle brakes, such as disc brakes (fig. 11) and linear-pull
brakes (fig. 12), are extremely powerful. Take extra care in becoming
familiar with these brakes and exercise particular care when using them.
4. Some bicycle brakes are equipped with a brake force modulator, a
small, cylindrical device through which the brake control cable runs and
which is designed to provide a more progressive application of braking
force. A modulator makes the initial brake lever force more gentle,
progressively increasing force until full force is achieved. If your bike is
equipped with a brake force modulator, take extra care in becoming familiar
with its performance characteristics.
5. Disc brakes can get extremely hot with extended use. Be careful not to
touch a disc brake until it has had plenty of time to cool.
6. See the brake manufacturer’s instructions for operation and care
of your brakes, and for when brake pads must be replaced. If you do not
have the manufacturer’s instructions, see your dealer or contact the brake
manufacturer.
7. If replacing worn or damaged parts, use only manufacturer-approved
genuine replacement parts.
lever should leave a clear imprint in the palm of your hand.
(7) With a through-bolt or bolt-on system, tighten the fasteners to the torque
specifications in Appendix D or the hub manufacturer’s instructions.
NOTE:
If, on a traditional cam action system, the lever cannot be pushed all the
way to a position parallel to the seat stay or chain stay, return the lever to the
OPEN position. Then turn the tension adjusting nut counterclockwise one-quarter
turn and try tightening the lever again.
WARNING: Securely clamping the wheel with a cam action retention
device takes considerable force. If you can fully close the cam lever
without wrapping your fingers around the seat stay or chain stay for
leverage, the lever does not leave a clear imprint in the palm of your hand,
and the serrations on the wheel fastener do not emboss the surfaces of the
dropouts, the tension is insufficient. Open the lever; turn the tension
adjusting nut clockwise a quarter turn; then try again. See also the first
WARNING in this Section, p. 18.
(8) If you disengaged the brake quick-release mechanism in 3. c. (2) above,
re-engage it to restore correct brake pad-to-rim clearance.
(9) Spin the wheel to make sure that it is centered in the frame and clears the
brake pads; then squeeze the brake lever and make sure that the brakes are
operating correctly.
B. Seat post cam action clamp
Some bikes are equipped with a cam action seat post binder. The seat post
cam action binder works exactly like the traditional wheel cam action fastener
(Section 4.A.2) While a cam action binder looks like a long bolt with a lever on
one end and a nut on the other, the binder uses an over-center cam action to
firmly clamp the seat post (see fig. 8a).
WARNING: Riding with an improperly tightened seat post can allow
the saddle to turn or move and cause you to lose control and fall.
Therefore:
1. Ask your dealer to help you make sure you know how to correctly
clamp your seat post.
2. Understand and apply the correct technique for clamping your seat
post.
3. Before you ride the bike, first check that the seat post is securely
clamped.
Adjusting the seat post cam action mechanism
The action of the cam squeezes the seat collar around the seat post to hold
the seat post securely in place. The amount of clamping force is controlled by the
tension adjusting nut. Turning the tension adjusting nut clockwise while keeping
the cam lever from rotating increases clamping force; turning it counterclockwise
while keeping the cam lever from rotating reduces clamping force. Less than
half a turn of the tension adjusting nut can make the difference between safe and
unsafe clamping force.