Bike Repair & Maintenance For Dummies®
Page 13
1. Pinch the brakes together and lift the end of the cable up and out of the quick release in the brake arm where the cable sits (as shown in Figure 8-6).
Figure 8-6: Undoing the quick-release.
2. Undo the bolt that holds the brake onto the pivot (as shown in Figure 8-7).
Be careful as you loosen the bolt, because the spring may cause the brake arms to snap back or parts such as washers to shoot off the brake.
3. Pull the brake off the boss (as shown in Figure 8-8).
4. To remove the pad in cartridge-brake shoes, look for a small screw or pin holding the pad in place and remove it as shown in Figure 8-9.
Figure 8-10 shows how the pad slides off once the pin is removed. If there isn’t one, use a screwdriver to pry the pad off.
Figure 8-7: Loosening the brake.
Figure 8-8: Removing the brake.
Figure 8-9: Removing the brake-pad pin.
Figure 8-10: Removing the brake pad.
Here’s how to remove center-mount brakes:
1. Loosen the cable anchor bolt and remove the cable.
2. Using an Allen wrench or a 10mm open hex wrench, loosen and remove the center bolt mounting nut on the back and remove the complete brake caliper.
3. To remove the pad in cartridge brake shoes, look for a small screw or pin holding the pad in place and remove it (refer to Figure 8-9).
Refer to Figure 8-10 to see how the pad slides off once the pin is removed. If there isn’t one, use a screwdriver to pry the pad off.
Some bikes don’t have cartridge brake shoes and have non-replaceable brakes pads. If your bike falls into this category, think about changing to replaceable pads, especially if you ride a lot and will go through pads relatively quickly. With the cartridge pads, you slip a new pad into the brakes and you don’t have to readjust the alignment and angle of the brake shoes every time they’re replaced.
Installing brakes
After you’ve reattached the brake pads, you’re ready to reinstall the brakes. To install cantilever brakes, follow these steps:
1. Apply a small amount of grease to the bosses, the frame post that the brake arms mount to.
2. Slide each brake arm onto a boss, inserting the small pin at the end of the brakes’ coiled spring into the middle hole.
3. Insert the pivot bolt into the boss and tighten it with an Allen wrench.
4. Run the end of the cable through the cable clamp and, while squeezing the brakes against the rim with one hand, tighten the cable clamp bolt with the other.
Bike shops often use a fourth-hand tool to help tighten the brake cable (see Figure 8-11).
To install V-brakes, follow these steps:
1. Apply a small amount of grease to the pivots.
2. Slide each brake onto a pivot, inserting the small pin at the end of the brakes’ coiled spring into the middle hole.
The top hole will give that side of the brake more recoil tension and the lower hole will give that side less recoil tension. These are used if the fine-tuning spring adjustment is not enough (see “Adjusting Brakes,” later in this chapter).
Figure 8-11: Using a fourth-hand tool.
3. Insert the pivot bolt into the boss and tighten with an Allen wrench.
4. Pass the cable wire through the metal curved tube (called the noodle) that comes with the brakes.
5. Insert the metal tube with cable wire into the slot in the cable holder until the tip is poking out through the other end and is firmly in place.
6. Insert the cable wire into the rubber sleeve and slide the sleeve onto the tip of the metal tube.
7. Run the end of the cable through the cable clamp and, while holding and squeezing the brakes against the rim with one hand, tighten the cable clamp bolt with the other.
Bike shops often use a fourth-hand tool, which eliminates the need to hold the brakes together (refer to Figure 8-11).
To install center-mount brakes, follow these steps:
1. Examine and make note of the spacers and washers on the front and rear center mounting bolts.
Sometimes they have moon-shaped spacers that need to go next to the front and/or back part of the frame or fork. Other times, they use a recessed mounting nut with the lock washer on the side closest to the brake caliper, or just a standard nut with the lock washer on the back side next to the nut. The front brake will usually have the longer center mounting bolt.
2. Remove the nut, spacers, and washers that will be on the inside of the frame or fork, and insert the center mounting bolt through the hole either in the fork or the rear brake bridge.
3. Install the remaining spacers and washer.
4. While holding the brakes so that they’re centered over the rim, tighten with the nut.
5. Run the end of the cable through the cable housing stop, and then through the cable clamp and, while squeezing the brakes against the rim with one hand, tighten the cable clamp bolt with the other hand.
6. Set your pads and make your final adjustments (see “Adjusting Brakes,” next).
7. Trim the excess cable to about 2 inches, and put a cable end cap on it so it doesn’t fray.
Adjusting Brakes
Adjusting your brakes is important to ensure that you can slow down or come to a stop quickly and effortlessly each time you squeeze the brake levers. In this section, we tell you how to adjust your brakes in order to maximize their effectiveness.
Sometimes brakes are a little temperamental when it comes to adjustments. Just have a little patience and try not to get temperamental yourself when it takes several tries to get the position just right. With a little practice, you’ll be able to do it in a snap.
Adjusting brake-pad position
In order for your brakes to grab the rim of your bike’s wheel firmly, they need to be in the proper position. Follow these steps to adjust your brakes’ position:
1. Hold the brake pad with one hand and undo the nut or bolt holding the brake shoe one or two turns to loosen it just slightly (see Figure 8-12).
2. Squeeze one of the brake levers so that the pad is pressed up against the rim.
3. While holding the lever with one hand, position the pad so that it lines up parallel with the rim. Also adjust the pad so that the front part of the pad is closer to the rim than the back part.
This alignment of the brake pads is called toe in.
Some brakes have concave and convex washers to help with the toe-in adjustments. Sometimes, with center-mount brakes, you need to put an adjustable wrench on the brake arm itself and bend it slightly to make the toe-in adjustment.
4. Hold the pad in place and release the lever. As you’re holding the pad, tighten the bolt to secure the pad in its current position.
5. Repeat steps 1 through 4 for the other brake pad.
When you’re finished, the front part of the brakes should be angled in slightly (toe in) such that that the end of the brake pads closest to the front of the bike is 1mm from the rim and the back part of the brakes pads are 2mm from the rim.
Figure 8-12: Adjusting the brake.
Centering and tensioning brakes
To ensure that your brakes operate as they were designed, you may need to make some adjustments to their position. These adjustments include centering the brakes so that the brake pads are aligned evenly with the rim. You may also have to adjust the tension so that the brakes remain within a millimeter or two from the rim and will grab the rim with the slightest grip of the brake lever.
There are a few general rules of thumb you can keep in mind when making adjustments:
You shouldn’t be able to “bottom out” the hand levers against the handlebars while fully clamping down on the brakes.
&nbs
p; Your brakes shouldn’t rub the rims.
You shouldn’t be able to push the front or rear wheel and get it to move while the brakes are applied.
The front and rear brakes should feel relatively even in brake lever tension.
Adjusting brake tension
With properly tensioned brakes, the brake pads should be positioned 1mm to 2mm from the rim and easily grab the rim when the brake lever is squeezed. To adjust the tension, you can do a few things:
Some brakes have a small screw at the bottom of the brake arm, which allows for small adjustments to be made to the distance between the rim and the pads. Turning the screw clockwise will move the pad away from the rim; turning the screw counterclockwise will move the pad closer (see Figure 8-13).
Another possibility is to adjust the barrel adjuster at the brake levers or at the brakes. Turn the adjuster one turn, and note the results adjusting for more or less tension.
You can also try removing both of the brake arms and changing the frame mounting hole in which the spring pin is inserted. Reinstall the brake spring in the top or the highest of the three holes. Readjust the brake and check the results.
If the fine-tuning of the screw, barrel adjuster, and spring pin is not enough to increase tension on the brakes, you’ll have to loosen the cable bolt (which holds the cable in place), pull the cable tighter, and retighten the bolt. Special tools can facilitate this procedure including a third-hand tool (which holds the brakes together) and a fourth-hand tool (which pulls the cable tight). With four hands working for you, you can’t go wrong!
Figure 8-13: Adjusting brake tension.
Centering your brakes
In most cases, your brakes should be symmetrical and an equal distance from the wheel rim. If one of the brake pads touches the rim before the other or, even worse, rubs on the rim while you’re riding, an adjustment to center the brakes may be needed.
Before you center the brakes, make sure that:
Your wheel is centered in the frame or fork.
Your wheel is trued.
Your wheel is spinning straight.
If your wheel isn’t centered, true, and spinning straight, what may appear like a brake being off-center may be the wheel wobbling toward one of the brakes. (See Chapter 7 for how to make adjustments to your wheel.)
The procedures for centering brakes may vary slightly depending on what type of brakes you have, but here are some strategies you may be able to try:
If the brakes have a small screw, try adjusting it with a screwdriver or Allen wrench and note the result.
In some cases, with center-mount brakes, you may need to rotate the entire brake caliper on the center mounting bolt to get the desired result. Try loosening the mounting bolt, rotating the brake, and then retightening it.
The brakes may have different spring tensions. If so, try removing one of the brake arms and changing the frame mounting hole in which the spring pin is inserted. Reinstall the brake and check the results.
You want to have the adjusting barrels unthreaded (counterclockwise) one or two revolutions when you’re finished with your brake adjustments. This allows you to thread them back in (clockwise) if your rim comes out of true on a ride so your brakes aren’t rubbing and slowing you down.
To center dual-pivot brakes with a quick-release lever, you can adjust the brake tension using an Allen wrench or screwdriver. First, open the quick-release lever to remove tension on the cable (as shown in Figure 8-14). Then, using the Allen wrench or screwdriver, turn the adjuster clockwise or counterclockwise to make the space between the rim and the brake pads equal on both sides (see Figure 8-15). You can also make smaller, fine-tuning adjustments by turning the barrel adjuster (see Figure 8-16).
Figure 8-14: Moving the lever on center-mount brakes
Figure 8-15: Adjusting center-mount brakes.
Figure 8-16: Adjusting the cable on center-mount brakes.
Silencing those squeaking brakes!
Probably one of the biggest issues with brakes is squeaking. Coming to a stop with a loud screech that makes everyone look up at you is no fun — unless you use the screech in place of a bell or a horn. People will certainly get out of your way!
One of the biggest causes of squeaking is improperly positioned brake pads. If your brakes squeak, try adjusting the pads, as described in the “Adjusting brake-pad position” section, so that the front part is toed inward toward the rims (see Figure 8-17). Many types of brakes have spacers on the pad holder that can be adjusted to move the pad into the proper position. Loosen the mounting bolt and then use your hand to move the spacers and the pad. When you find the toe-in position, tighten the bolt.
Figure 8-17: Proper brake alignment.
Another possible cause of squeaking is dirty or oily rims. If you haven’t cleaned your rims in a while, use some rubbing alcohol and a rag, and wipe them down. To keep them clean going forward, wipe the rims with a damp rag each time you finish a ride.
In some cases, squeaking is caused by brake pads that have hardened over time. If your brakes are more than a few years old try replacing them to eliminate the noise.
Finally, inspect the brake pads for foreign debris. Something wedged into the rubber may be causing the squeal.
Using the brake quick release
Many brakes are designed with a quick-release capability that makes it easy to spread them apart when you need to remove the wheel. This quick release may also be used if you badly bend your wheel rim and the rim is rubbing the brake pads.
Riding with the quick release engaged will greatly reduce the effectiveness of your brakes.
The quick-release mechanism — which may be a button, a lever, or an easy way to detach the cable — differs depending on the type of brake:
For cantilever brakes, squeeze the brake arms together with one hand to create slack in the cable and, with the other hand, lift the loose end of the cable out of its pocket. Release the breaks and they’ll pop open.
For V-brakes, pinch together the top of the brake arms to loosen the cable. Pull the rubber boot back to expose the cable (see Figure 8-18). Carefully pull the cable out of the narrow slot in the cable holder and release it to open the brakes (see Figure 8-19).
Figure 8-18: Releasing V-brakes.
Figure 8-19: V-brakes released.
For center-mount brakes, look for a small lever on the side of the caliper where the cable is attached (refer to Figure 8-14). Pull it upward and release the brakes just enough to allow the wheel to pass. In some models, you’ll need to look for a button on the hand lever and push it to release the tension on the brakes.
If you can’t find the release on your brakes, examine the brake levers. On some bikes, there is a quick-release button on the brake lever. Push it to increase the clearance between the brake pads.
If you’re trying to remove the tire but you can’t figure out how to open the brakes, try letting air out of the tire. This will reduce the width of the tire and may allow it to pass between the brake pads. After you put the wheel back in place, reinflate it.
Replacing brake cables
Brake cables are a critical component of your braking system. You can have new brake pads, but if your brake cables give out, you won’t be able to stop your bike when you need to. Each time you give a hard squeeze to your brake levers, the cables must transfer that force to the brake pads. Over time, this force will wear out the cables, causing them to kink, fray, or bend. If you see these signs of wear with your brake cables, do the safe thing and change them immediately. Here’s how:
1. Unfasten the brake cable by loosening the nut or bolt where the cable attaches to the brake arm.
2. Squeeze the brake lever so that the nipple at the end of the cable is showing.
3. Grab the end of the ca
ble with a pair of pliers and pull the cable slightly out from the brake lever.
Before you remove the brake cable, take a moment to observe how it is routed around the frame of the bike. Pay attention to the location of the cable housing and where the cable housing meets the cable stops and the cable exits on the other side. You’ll need to route the cable and cable housing in the same manner when you reinstall it. You want the housing to be as short as possible. The housing should have gradual curves with out any binding or sharp angles.
4. Once you grab the cable, use your hands to remove the entire length of the cable (see Figure 8-20).
5. Collect any ferrules that were holding the cable housing in place at the anchor points.
You’ll use these when you reinstall the cable.
It’s a good practice to change the cable housing when you replace cable wires. Manufacturers often sell cable with the housing included in the package. They normally give you more housing than you need so you’ll have to cut it to fit your bike.
Figure 8-20: Removing the cable.
6. Cut the cable housing with cable cutters (see Figure 8-21).
Cable cutters are useful because they cut the housing without compressing the end too much. Assuming the old housing was the proper length, use the older pieces of cable housing as guides for cutting the new pieces.
Even if you use a cable cutter, you may need to file the end of the cable if it has any sharp edges. You may also need to open the end of the housing up with an awl or other pointed instrument if the end looks like the example on the left in Figure 8-22.
7. When you’re ready to install the new cable, use a rag to apply a light coating of grease to its surface.