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DISC
BRAKES
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Disc brakes & how they
operate |
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Buying Info |
Forks |
Full Suspension |
Hardtails |
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1 The Rotor or Disc:
The rotor is normally manufactured from
stainless steel. The rotor acts as the
braking surface for the brake calliper. It
effectively replaces the braking function of
the rim in a conventional brake set-up. Six
hole drillings have become the standard
fixing method. Larger rotors give greater
stopping power.
2 The Brake Hose:
On hydraulic systems the brake hose contains
either DOT4 or mineral oil, depending on the
manufacturer's choice. On mechanical disc
brakes the brake hose is replaced with
conventional brake outers and contains a
standard brake cable.
3 The Calliper:
The calliper is anchored to the fork / frame
via two fixing bolts. Pulling on the brake
levers pushes hydraulic fluid into the
callipers, pushing the pistons and the pads
towards the disc, creating the braking
force.
4 The Fixing Bolts:
Allen and Torx bolts are the most common
method of attaching the disc to the hub.
Always follow the manufacturers guidelines
for installation and torque settings. Be
careful not to strip or snap the heads of
the bolts.
5 The Bleed Nipple:
This is where you get hydraulic fluid into
and out of the system via the bleed nipple.
6 The Piston:
Lightweight alloy pistons in the calliper
are worked by the fluid in the hydraulic
system, or a helix in a mechanical brake,
and move the brake pads towards the rotor.
Open systems have self-modulating pistons
that maintain a constant distance between
the pads and the rotor. A closed system and
mechanical system use springs to return the
pistons / pads to the rest position and do
not compensate automatically for pad wear.
7 The Brake Pads:
Just like normal V brake pads, disc brake
pads are available from a variety of
manufacturers. Pads are not usually
interchangeable between different brake
systems, so it's important to get the right
ones for your system. You can buy brake pads
with different compounds to suit the
individual needs of the rider or the
conditions. Swapping pads can dramatically
alter the characteristics of the brake, so
have a go.
8 Pad Retaining Pins:
Split-pins and Allen bolts are common, while
some manufacturers use small spring clips on
the back of the pads to fasten them securely
in place. They are a very important part of
the set-up, forget to re-place them and as
soon as the brake is applied they will shoot
out. |
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WORKINGS OF A DISC BRAKE:
Is based on 3
principals:
1) Leverage
2) Hydraulic multiplication
3) Friction |
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As you can see in the animation, the
hand-force is multiplied by the
brake lever. Next hydraulic
multiplication increases the
pressure on the disc brake pistons.
(Size difference between the pistons
from the brake lever and -
calliper).
When the brake-pads are pushed
against the rotor, the friction
between these two and the tires and
road, makes your bike slow down or
stop. |
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BUYING INFO |
Will I need to buy new brake levers?.
If you buy hydraulic disc brakes, then
the system will come with the levers and
callipers. Mechanical disc-brakes use a
conventional brake cable so it is simply
a case of attaching your brakes to your
existing V-brake levers. This option is
worth considering if your shifters and
brake levers are all one unit. |
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Why buy disc brakes?.
The main advantage of disc brakes over
conventional V's is the consistency of
braking performance. Because the braking
action is taken away from the rim and
concentrated at the disc, the entire
system is less affected by the elements.
Mud clearance take on a new meaning,
while buckles and dints in the rims are
no longer an issue. Another plus is that
most hydraulic systems are virtually
maintenance free, so leaving the bike
covered in shit will not damage the
braking system, but it will knackered
the rest of your bike. |
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