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Linear-pull
(V-brake) adjustment - part identification |
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Brake Lever: mounting
bolt, reach adjustment screw, pivot, barrel adjuster and lock ring. |
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| Fig 1 |
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Brake assembly: brake arms, mounting
bolts, cable pinch bolt, return springs, centering screws. |
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| Fig 2 |
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Brake assembly (continued): noodle, cradle, boot. |
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| Fig 3 |
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Brake pad: mounting nut, concave/convex washers. |
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| Fig 4 |
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(c) Copyright
2006 Community Exchange Bike School. |
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All Rights
Reserved. ExchangeCycleTours.org |
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Last Updated:
11/20/2006. |
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Brake cable: end cap, ball end. |
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| Fig 5 |
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Brake cable housing: ferrules, housing stops. |
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| Fig 6 |
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Linear-pull
(V-brake) pre-adjustment inspection |
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a) Check that the wheel
is seated flush in the dropouts and is trued and centered. |
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| Fig 7 |
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(c) Copyright
2006 Community Exchange Bike School. |
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All Rights
Reserved. ExchangeCycleTours.org |
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Last Updated:
11/20/2006. |
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b)
Check that the brake assembly is properly mounted, relatively centered,
and that the brake arms move freely |
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without
flopping. Check that return spring
is in place and not broken. Also, make sure the spring is inserted into
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the center hole on the
brake boss (part of the frame where the brakes attach). |
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| Fig 8 |
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The mounting bolts should be snug, but not super tight. |
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c)
Check the brake levers for damage, working barrel adjusters, mounting bolts,
and working return |
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springs if applicable. |
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d)
Check the brake housing for damage, sharp bends, and proper length to allow
movement without sharp |
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bends.
Make sure the cable stops on the frame are in good condition, and that there
are ferrules on the |
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housing ends. |
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| Fig 9 |
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(c) Copyright
2006 Community Exchange Bike School. |
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All Rights
Reserved. ExchangeCycleTours.org |
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Last Updated:
11/20/2006. |
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Linear Pull (V-brake) Adjustment |
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1. Set lever position and angle (optional) |
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To
a large extent, the position of the brake levers is a matter of personal
preference. However, the following
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procedure should be done
if the levers are grossly out of position. |
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| Fig 10 |
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Loosen the mounting bolt/nut,
position lever on handlebar and set at 45 degrees to the ground. |
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Tighten the mounting hardware. |
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| Fig
11 |
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| Fig 12 |
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Use the reach adjustment screw
to set the distance between the lever and the handlebar to allow a comfortable
reach. Turning it clockwise will move the lever closer to the bar. |
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(c) Copyright
2006 Community Exchange Bike School. |
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All Rights
Reserved. ExchangeCycleTours.org |
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Last Updated:
11/20/2006. |
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2. Adjust brake pads |
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It's important that the
brake pads contact the rim squarely and in the center of the braking surface.
A misaligned |
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pad may slide off the rim and into the tire or spokes. |
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| Fig 13 |
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Most linear-pull brakes use brake
pads with convex and concave washers which allow them to be angled in any
direction. |
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Also
notice that there are two thicknesses of concave washer on each pad. That
is so you can adjust how far the pads extend from the brake arms.
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| Fig 14 |
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The pads should follow the curve of the rim. |
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(c) Copyright
2006 Community Exchange Bike School. |
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All Rights
Reserved. ExchangeCycleTours.org |
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Last Updated:
11/20/2006. |
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| Fig 15 |
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They should be centered
vertically on braking surface of rim. |
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| Fig 16 |
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And they should contact the rim
at a 90 degree angle to the braking surface. |
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Ideally, at the point of contact,
the brake arms should be at a 90 degree angle to the pads as well. If your
brake arms are at an extreme angle to the pads when the pads contact the
rim, you may need to swap the washers on the brake pad. |
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Generally, brake pads
are set up with toe-in. Toe-in means the leading edge of the pad touches
the rim before |
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the
trailing edge. This counteracts the torque imparted on the brake by the
rim and stops squealing. The standard
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amount
of toe-in is 1mm (the trailing edge of the pad will be 1mm from the rim
when the leading edge makes |
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contact). |
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Many
linear-pull brakes, however, use asymmetrical pads which are designed to
be used with no toe-in. |
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They don't require toe-in
because the longer rear section of the pad resists the twisting forces exerted
on it by the |
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wheel. |
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So the rule of thumb is,
if you have asymmetrical pads set them up without toe-in and only add |
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it if necessary. If your
pads are symmetrical set them up with 1mm of toe-in. |
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| Fig 17 |
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Symmetrical pads should have about 1mm of toe-in. |
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(c) Copyright
2006 Community Exchange Bike School. |
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All Rights
Reserved. ExchangeCycleTours.org |
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Last Updated:
11/20/2006. |
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| Fig 18 |
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Set asymmetrical pads so they
are parallel to the rim when viewed from above. |
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(Pretend the pad in the picture is asymmetrical) |
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| Fig 19 |
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Brake pads should be adjusted
one at a time. Loosen the brake pad mounting bolt just enough to allow the
pad to move. |
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Keeping your wrench in the brake
pad mounting bolt, manipulate the pad with your other hand. |
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Make small adjustments and check
frequently by snugging up the bolt and pushing the brake pad against the
rim while watching to see how it hits. |
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A
method which can greatly simplify adjustment is to release the spring on
the side you are adjusting and let |
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the spring
in the other arm pull the pad against the rim. |
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| Fig 20 |
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The spring rests on a little
knob on the brake arm. To disconnect it, push the spring in toward the wheel
and move it to the side. |
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(c) Copyright
2006 Community Exchange Bike School. |
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All Rights
Reserved.
ExchangeCycleTours.org |
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Last Updated:
11/20/2006. |
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| Fig 21 |
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The spring's pressure will open it away from the wheel. |
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The brake pad will be pulled
against the rim by the spring in the opposite brake arm. |
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Now you all you have to do is
adjust the pad so it makes even contact with the rim. |
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If
you need to add toe-in you can use your Allen wrench (in the mounting bolt)
as a lever to angle the pad so the trailing edge is 1mm from the rim. |
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Check adjustments by reseating
the spring and squeezing the lever. |
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3. Balancing the brake spring tension. |
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For
a firm feel at the lever, and to make sure one pad doesn't drag on the rim
as you ride, brakes need to be |
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centered so that both
pads contact the rim at the same time. |
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| Fig 22 |
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Most
linear-pull brakes come equipped with spring tension screws. These screws,
located at the base of the brake arms, adjust the tension on the brake return
springs. |
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Increasing the tension (turning
the screw clockwise) on a particular arm will move that arm further from
the rim. Turning the screw counterclockwise will move that arm closer to
the rim. |
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To preserve the overall tension
on the brake, you should make adjustments using both screws. For instance,
to move the brake to the right, tighten the right screw and loosen the left
screw by the same amount. |
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| Fig 23 |
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A
good way to check that both pads are contacting at the same time is to give
the wheel a spin and squeeze the lever gradually until one of the pads rubs
the rim and stops the wheel (hold the lever still as soon as you detect
contact).
Then, squeeze the lever further and observe which pad continues to move
toward the rim. If the right pad moves, the brake is too far to the right,
if the left moves, it’s too far to the left. |
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4. Lube the cables. |
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For the brakes to function
efficiently, the cables should be lubed where they pass through the cable
housing. |
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| Fig 24 |
Create slack in the cable by disconnecting the brake. |
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To disconnect the brake, pull
the noodle and the cradle apart and lift the noodle out of the slot. |
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You may have to shove the rubber
boot out of the way first (toward the cable cinch bolt). |
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| Fig 25 |
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If you can't pull the cradle
and noodle far enough apart to disconnect them, you can create create slack
in the cable by loosening the cable anchor bolt, freeing the cable. |
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(c) Copyright
2006 Community Exchange Bike School. |
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All Rights
Reserved. ExchangeCycleTours.org |
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Last Updated:
11/20/2006. |
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| Fig 26 |
Disconnecting the noodle. |
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| Fig 27 |
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Once the brakes are disconnected
there should be enough slack to remove the cable housing from the housing
stops on the frame. |
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Slide the housing back out of
the stop and lift the cable through the slot in the stop. |
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| Fig 28 |
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Slide the housing along the cable
to expose the hidden sections of cable. |
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Apply a thin coat of oil to the cable (Tri-Flo works well). |
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Move the housing back into position
and reseat the cable, return the noodle to its home, and reattach the cable
if necessary. Give the lever a few squeezes to distribute the oil
in the housing. |
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5. Seat the cables. |
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Before
adjusting the brake cable, it's a good idea to give the lever a few squeezes
to make sure all cable housing |
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is fully seated in the cable stops and barrel adjusters. |
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| Fig 29 |
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At this point you should also
do a visual inspection to make sure all housing is in place. |
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(c) Copyright
2006 Community Exchange Bike School. |
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All Rights
Reserved. ExchangeCycleTours.org |
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Last Updated:
11/20/2006. |
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6. Set brake cable tension. |
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The cable tension controls the distance
between the brake pads and the rim. A cable that is set too tight will hold |
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the pads too close to the wheel causing
them to rub the rim as you ride. A cable that is too loose results in brakes |
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that feel "soft" or are
ineffective because the lever goes all the way to the handlebar before the
brake engages. |
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| Fig 30 |
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First, screw the barrel adjuster
on the brake lever all the way in (clockwise). Then back it out one turn
(counterclockwise). This will provide
room for fine tuning later. |
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On
linear-pull brakes, it's important that there is not too much cable tension
to prevent you from being able to |
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unhook the saddle and open the brakes in the future. |
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| Fig 31 |
A good way to ensure there is
enough slack to unhook the noodle is to adjust the cable tension with the
noodle partially unseated. |
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Pull the noodle and cradle apart
as if you were opening the brake, but don't lift it out of the cradle. Hook
it against the cradle as shown. |
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| Fig 32 |
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Loosen the brake cable pinch
bolt on the brake arm enough to free the cable. |
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| Fig 33 |
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Use
one hand to both brace against the brake arm and pull the cable throught
the cinch bolt as shown. |
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Pull the cable through the cinch
bolt until the pads contact the rim. |
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With your other hand, tighten up the cinch bolt. |
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Reseat the noodle, allowing the
pads to move away from the rim, and check the adjustment. |
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| Fig 34 |
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The brakes should engage when
the lever has travelled about 1/3 of the way to the handlebar. |
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(c) Copyright
2006 Community Exchange Bike School. |
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All Rights
Reserved. ExchangeCycleTours.org |
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Last Updated:
11/20/2006. |
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| Fig 35 |
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At
this point, small adjustments can be made with the barrel adjusters (be
sure to lock the barrel locknuts to preserve your adjustment settings).
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It's
important that the barrel adjuster has no more than a few (3 for example)
threads exposed. This allows for future adjustability and prevents strip-out.
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Any large change in the cable
tension should be done by reanchoring the brake cable, not by backing out
the barrel adjuster. |
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7. Final check |
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Squeeze the levers a few
times, make sure they feel good and that both levers engage similarly. Spin
the wheel |
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and look and listen for
any rubbing. Take the bike for a ride to test the brakes. They should stop
quietly, smoothly, |
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and effectively. |
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If your brakes squeal,
try giving them some toe-in or increasing the toe-in. |
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On certain low-end generic
brake pad/rim combinations, it may be impossible to eliminate all brake
squeal. |
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