In this video we will walk through the mounting
and adjustment for the linear pull rim caliper brake.
Make sure you're watching the caliper mounting and adjustment video that matches your brake type.
If you're not sure what you're dealing with,
watch this video.
The linear pull brake may be found on the
rear or the front of the bike.
Pivots for the brake are located below the
braking surface.
Left and right arms are pulled together by
a single primary wire.
A housing stop is attached to one arm.
The cable extends to the other arm with a pinch bolt.
Pulling the lever brings the pads to the rim.
Typical tools and supplies may include:
hex wrenches for brake caliper mounting and pad adjustment
A "fourth-hand" cable stretcher
torque wrench and bits to make sure things
are properly tight
screwdriver for brake centering
a cable cutter to trim the brake cable and to install the end cap
grease, a rag, and threadlocker
The linear pull brakes mount to the same
frame fittings as the cantilever brake.
The outside of this surface should get some
grease to help them run smooth and not blind.
Do not grease or lubricate the inside threads.
There is typically a thread locker on the bolt,
or if there's none here, threadlocker could be put inside.
Grease on the threads would eliminate the purpose of the thread locker.
The brake calipers have a spring that will
insert into one of three possible fittings.
The top-most fitting provides a lot of spring tension.
It is common you may have to
twist the pad to get past the fork.
Here, it almost feels like there's too much tension.
The bottom-most hole provides very little tension.
Typically, select the middle hole and make sure that both sides are symmetrical and in the same middle hole.
Mounting bolts are now threaded into each
side.
If there is pre-installed
threadlocker on the bolt,
it is normal to feel a little resistance
as it threads in.
That is the threadlocker doing its job.
A typical torque for the mounting bolts is
8 to 10 Newton meters.
The arms should still swing freely.
After the arms are secure to the frame or
fork, the pads are now adjusted.
The common linear pull will have a threaded stud system.
There's a series of convex and concave
washers that create a ball and socket system.
This will allow for alignment on several
planes: it will allow for toe,
it will allow the vertical face of the pad
to be square to the rim,
we can move up and down in our brake arm for
height
Everything is secured with a single nut
at the back of the brake stud.
It's also very common to notice the slight
curve in your brake pad.
This curve will match the curve of the rim.
Loosen the pad mount, bring the arm and pad
to the rim, and adjust.
Because we're traveling downward on an arc,
we want to be to the top edge of the braking surface,
not to the top edge of the rim, but the top of the braking surface.
As the pads get thinner, they will travel down the rim more and more.
Never have a pad so high it would hit a tire.
With the mounting nut loose, the tire will
want to move on lots of different planes.
Bring the pad gently to the rim and push with
some mild force and secure the nut.
The pad will tend to be self-aligning and
put the convex-concave washers where it needs
to be correctly aligned with the two flat
surfaces - the rim and the pad - aligned.
Toe can be had a couple of different ways.
Loosen the nut and bring the wrench forward or
back as needed to gain toe.
Toe is useful to help reduce brake squeal.
As the rim rotates forward, the pad and the arm are going to pull back and forth slightly.
That can cause a squeal which is a harmonic resonance.
By introducing touch at the front
and a slight gap at the back,
we are reducing the tendency of the arm
and pad to move back and forth quickly -
that reduces squealing.
We begin with the correct height
We check that the front and back edge are
square and even to the rim
So for toe, we loosen the nut pull the wrench
forward in this case, and secure.
Here - far too much toe.
With huge amounts of toe, you're reducing braking performance
as it flexes to come in and apply force to the rim.
So a slight gap is what we're looking for.
Bring the wrench to the back slightly
Hold and secure.
A slight gap at the back,
front edge and back edge even, we're flat to the rim
Typical torque here - 6 to 7 Newton meters.
Hold the pad as you tighten the final tightness
so it doesn't twist as you tighten the mounting nut.
Repeat the process on the other side.
A second useful technique to get some toe
is to put a shim at the back edge of the pad,
align our pad fully to the rim,
secure the nut and remove the shim.
A rubber band closed up can act as that shim.
We'll place this on the back of the pad,
loosen the mounting nut,
and proceed to adjust our pad as normal.
Just some mild force to the rim is going to
move the stud in the washers to allow toe.
Secure the pad fully, remove the shim,
and we have a slight gap at the back from the shim.
Repeat the process on the other side.
The brake cable passes through the housing and the housing will be stopped at what is called a noodle.
The noodle acts as a stop for the housing
and the cable will pass out to the other arm,
allowing us to draw arms together.
A noodle typically consists of a liner
underneath the housing stop.
This is a common place to get
a lot of moisture and corrosion -
consequently, it's a good
place for lubrication.
Install the wire through the noodle and out.
The noodle will engage in the linkage off one arm
and pass over to the pinch bolt on the opposite arm.
It is common to see a dust boot
attached at this point
the idea being it's going to keep dirt out of the system.
So from here, we feed through the pinch mechanism
and before we draw the pads together, back
out the barrel adjusters three or four turns
so we can have some
fine tuning adjustments at the lever.
With the housing fully secure in the noodle,
the noodle is secured and seated in the linkage,
we are ready to draw the arms to the rim.
We can do this with a "fourth hand"
such as the BT-2.
It's only necessary to touch the rim
or even get really close.
Don't go all the way and squeeze with force -
you won't have enough adjustment
to make a good setting.
So it's simply to the rim, then secure the pinch bolt.
If you don't have a fourth hand, you typically can just pull the arms together just with your hand
and pull the cable out.
You have a lot of leverage on these arms - it doesn't take a lot of force to pull these pads together
so typically just using the hand is enough.
Here again we're tightening the pinch bolt.
It should flatten and crush that cable.
Here, 6 Newton meters is a good average torque.
We'll now set the pad clearance at the rim
by the feel at the lever.
If the pads are too tight,
the lever is going to pull and immediately engage.
That is simply too close.
If the wheel comes out of true at all,
it's going to rub the pads.
Additionally, it really doesn't give us good
braking power.
Third problem - it's difficult to
disengage the quick release mechanism.
We should be able to pull out the linkage
from the noodle,
and here we are having trouble doing that.
This brake is set too tight.
Here, we'll bring the barrel adjuster in toward
the lever,
giving us more slack.
Here we have more travel -
that's good for our leverage at the hand.
We are well greater than an inch clearance
when we're contacting,
so we have plenty of brake power
and here we can disengage
and reengage our quick release easily.
This brake is not too loose,
it is not too tight,
we would set the rear brake the same way.
It's time now to center the brakes.
It's time now to center the brakes.
Centering is done by subtle changes in spring
tension.
One side, or commonly both sides, will have
a screw adjacent to the return spring.
By tightening the screw, you are increasing
tension on whatever side you tighten.
Here, we are not centered.
We have a large gap on the
rider's left and touching on the right.
Both pads are going to move together
but here, the right arm
is weaker compared to the left.
so I'm going to loosen this screw,
making this one a little more equal in strength
and if we went too far, we can tighten
and if it looks good, it is good.
Over here we could've tightened this screw
to draw the pads to the right,
we could tighten this screw to draw both pads
to the left.
Again, both pads are going to move
if you're just dealing with one of these screws
so you don't need to do both.
It's time now to trim the cable and
install the cable end cap.
It's also common on many of these brakes to
have a little place to tuck the wire away
so it's tucked cleanly.
So we actually want to cut right about here
where the thumb is,
we're going to pull that out
we're going to trim that
we'll put an end cap on
and we will crimp it.
Then tuck it back
Clean and out of the way.
These brakes are ready for the road.
And that concludes the process for brake caliper mounting and adjustment.
If you're looking for help on a different procedure relating to rim brakes, we've got a whole series
and watch this video for an explanation of
how we've organized our rim brake video content
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