Brakes - MARIN Bicycle Owner's Manual

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.
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
26
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.
1. Brake controls and features
It's very important to your safety that you learn and remember which brake
lever controls which brake on your bike. Traditionally, the right brake lever
controls the rear brake and the left brake lever controls the front brake; but,
to make sure your bike's brakes are set up this way, squeeze one brake
lever and look to see which brake, front or rear, engages. Now do the same
with the other brake lever.
Make sure that your hands can reach and squeeze the brake levers
comfortably. If your hands are too small to operate the levers comfortably,
consult your dealer before riding the bike. The lever reach may be
adjustable; or you may need a different brake lever design.
Most rim brakes have some form of quick-release mechanism to allow the
brake pads to clear the tire when a wheel is removed or reinstalled. When
the brake quick release is in the open position, the brakes are inoperative.
Ask your dealer to make sure that you understand the way the brake quick
release works on your bike (see figs. 12, 13. 14 & 15) and check each time
to make sure both brakes work correctly before you get on the bike.
2. How brakes work
The braking action of a bicycle is a function
of the friction between the braking surfaces.
To make sure that you have maximum friction
available, keep your wheel rims and brake
pads or the disk rotor and caliper clean and
free of dirt, lubricants, waxes or polishes.
Brakes are designed to control your speed, not
just to stop the bike. Maximum braking force
for each wheel occurs at the point just before
the wheel "locks up" (stops rotating) and starts
to skid. Once the tire skids, you actually lose
most of your stopping force and all directional
control. You need to practice slowing and
stopping smoothly without locking up a wheel.
The technique is called progressive brake
modulation. Instead of jerking the brake lever
to the position where you think you'll generate
appropriate braking force, squeeze the lever,
progressively increasing the braking force. If
you feel the wheel begin to lock up, release
pressure just a little to keep the wheel rotating
just short of lockup. It's important to develop
a feel for the amount of brake lever pressure
required for each wheel at different speeds and
on different surfaces. To better understand this,
experiment a little by walking your bike and applying different amounts of
pressure to each brake lever, until the wheel locks.
When you apply one or both brakes, the bike begins to slow, but your
body wants to continue at the speed at which it was going. This causes a
transfer of weight to the front wheel (or, under heavy braking, around the
front wheel hub, which could send you flying over the handlebars).
27