How to install the center pull?

Posted by tan xiao yan on

Center pulls tend to be found now on vintage road bikes with each arm having a separate pivot. They are pulled from the middle with the straddle wire carrier which is where we get the name- center pull. The arms tend to move up in an arc as they approach the rim. Inspect for the motion of any caliper arm because it tells us where to set the pad height. We want the pads on the lower edge of the braking surfaces so as they wear they will not climb up into the tire.

Typical tools and supplies.
Hex wrenches for mounting nut and brake pads, a torque wrench with correct bits, box end wrench such as a 10 millimeter, a fourth hand tool such as the BT2 cable stretcher, a cable cutter such as the CN 10, one or two adjustable wrenches for towing the arms.

Caliper installation.
The center pull is bonded to the frame with a mounting bolt. Install the brake through the mounting hole and install the nut tightening to approximately 6-7 Newton meters. However, on the center pull which differs from other brakes, it’s important we hold the brake and send it to the rim as we tighten. If you are significantly off-center and tighten fully the brake as you adjust the pads then you need to center it again later. So the brake needs to be centered to the rim before securing the mounting nut.install the center pull

Pad adjustment.
The typical center pull has a flat mount system. This means there’s limited motion of the pad. We can come up and down for height. The front and back edge can be set square to our rim. There typically is not a feature that will allow for tow nor there a feature that allows the vertical face of the pad to be aligned to the vertical face of the rim. Loosen the pad mounting nut. Bring the pad up then we’ll pull the arms to the rim and again let the bottom of the braking surface to be close to the bottom edge of the pad. As the pad thins and wears, it will tend to creep up and up the rim. So we come to the lower edge of the braking surface with the pad adjustment. Make sure the front and back edge are the same height to the rim. Secure the mounting nut fully. Typically 5 Newton meters is a common torque. When tightening, hold firmly onto the pad so it doesn’t rotate as you tighten. Repeat the process on the other side.

Cable attachment.
Back out the barrel adjuster two or three turns to give you enough room and enough slack. The straddle wire carrier will have a hole for the cable. Feed the cable through the hole and make the manufacturer’s logo facing forward. Pull the arms upward before securing the pinch bolt. There are different ways to get the pads to the rim before tightening the cable pinch bolt. You can feed the wire in front of the arms. Use a fourth hand tool to engage the wire and pull up the straddle wire carrier and tighten the straddle wire carrier pinch mechanism. When you are done, you will see that you’ve pinched and flattened the cable and the cable will no longer have a round shape.install the center pull

On the rear brake, use a simple toe strap or a zip tie and engage it around each arm. Squeeze the arms to the rim and pull the toe strap tight. The install the travel wire carrier and repeat the same process as the front brake.

Set pad clearance.
Do this by feeling the brake lever. If it’s too tight, you’re barely pulling the lever and the pads immediately contact with the rim. Then you need more slack in the system. Bring the barrel adjuster in to introduce slack. If it is too loose and you are nearly touching the handlebar, take the slack out with the barrel adjuster. If you don’t have enough range in your barrel adjuster you may need to take up the slack or introduce slack at the pinch bolt and nut.

Center the pads to the rim.
We want the pads to contact the rim at the same time. If one contacts first, it’s actually shoving the rim over toward the other pad. Center by using the bridge that connects both arm pivots. Put an adjustable wrench on the bridge and put a wrench on the back nut. The wrenches will move the same direction and the same amount that will center the brake, so they are going to touch at the same time.