BICYCLE BRAKE BASICS TUTORIAL
Figure 1 - A common side pull caliper brake
This is a short introduction to the various types of brakes you will find on a bicycle and how they operate. There are many styles and types of brakes available now, and like all things mechanical, there are certain types that are better suited to certain types of vehicles and some types that should be avoided. Currently, disc brakes are becoming the standard which is nice because they have come down in price and are far superior to pad style brakes in many ways.
The most inexpensive (and least effective) type of bicycle brake is the side pull caliper brake shown in Figure 1. This brake is as simple as it looks – just a pair of steel arms that act like pliers in order to push a pair of rubber pads onto the edge of the rim to creates braking friction. This type of brake has been around since the wooden wheel bicycle, and they are very easy to install and adapt to practically any cycle that has a standard rim.
The downside to this style of brake is that it offers barely enough stopping power to lock up a wheel, and when wet becomes practically useless. I sometimes use this style of brake as a front brake when I have a much better braking system on the rear such as a disc brake. I would not rely on this type of brake if it was the only brake on a cycle.
Figure 2 - Cantilever brakes on a front fork
A much better (and more modern) variant of the pad brake is the cantilever or “linear pull” brake shown on the front fork in Figure 2. Because of the way the cable force is applied to the arms, the leverage is so much better than the side pull brake, making these brakes highly effective. This style of bicycle brake is just as good as a disc brake, and is very easy to install and setup.
The cantilever brake does require a pair of cantilever “studs” be mounted to the frame in the proper position, but this is not difficult to do, as the studs can be cut from one frame and welded to another frame. These brakes suffer a bit of wet rim weakness as well, but will still have enough power to lock up a wheel even in the rain.
Figure 3 - Disc brake rotor and calliper
A disc brake is currently the ultimate option for braking power and smoothness on a bicycle, and because of its widespread use, disc brakes are affordable for the garage hacker. A disc brake has a caliper system that presses two brake pads onto a disc rotor (Figure 3) to create braking friction. Disc brakes have more than enough stopping power for even large cargo bikes, and are easily adapted to trikes and quads since the rotor can be mounted to an axle.
Disc brakes have smooth operation through their entire range, and are only slightly impaired by water, so they are also great for all weather use. Installation of a disc brake is slightly more involved than a pad brake, but the ability to adapt them to an axle makes them the best solution for delta trikes and quadcycles. A single disc brake is more than enough for a large cargo bike, although having two brakes is always preferred.
Figure 4 - A standard bicycle brake lever
Practically every type of bicycle brake will require a cable and some type of lever to activate it. The lever pulls the braided steel cable through the outer housing, transferring energy to the brake system. Most levers can move the inner cable about 1 inch, which is plenty of distance to allow for light braking all the way up to a full wheel lockup. A typical brake lever is shown in Figure 4, having a steel lever and a hard plastic body that can clamp to a handlebar. There are hundreds of styles of brake levers, but essentially they all do the same job - pulling a cable an inch or so.
Figure 5 - Brake lever adjustment points
Bicycle brakes allow for several adjustments that will change the level of braking power, speed of braking power, and cable tension. The easiest way to “fine tune” a bicycle brake is by adjusting the hollow bolt at the brake lever as shown in Figure 5. The bolt allows the brake to be compensated for pad wear without having to adjust the brake end of the cable or pads by simply altering the length that the outer cable shield is away from the entry point on the lever. If your brake pads are worn a bit, unscrewing this hollow adjuster bolt will “pick up” the slack. Figure 5 shows this bolt after unscrewing it about ¼ inch and then securing it with the locking nut (marked B).
The other lever adjustment (Shown as A) allows the lever return spring tension to be changed. Not all levers offer this adjustment. If a brake seems to rub after it has been engaged, the return spring may need to be tightened a bit, although this could also indicate a bad or rusted cable.
Figure 6 - Adjusting a cantilever brake
Cantilever style caliper brakes also offer a few points of adjustment as shown in Figure 6. The screw shown as (B) is another return spring adjuster that will help move the pads off the rim if the cables are a bit sticky. There is one screw on each side of the brake, as the adjustment may only be needed on one side. The point marked (A) is the bolt that locks the brake pad to the braking arm and it needs to be adjusted so that the brake pad contacts the rim perfectly as shown in Figure 6 when fully engaged. If the pad is not aligned properly, it will either offer poor braking or destroy the side wall of your tire.
Figure 7 - Side pull brake adjustment points
Side pull caliper brakes have a similar adjustment system as shown in Figure 7. At point (A), the brake pad is set up so that it makes perfect rim contact when fully engaged. At point (B), the hollow bolt allows the cable to be adjusted for brake pad wear by moving the bolt and then locking down the small lock nut. In extreme cases, it may be necessary to loosen the cable clamping bolt at point (C) to adjust the actual cable. Pads should lift completely away from the rim edge when not in use, yet have enough power to lock up a rim when fully engaged. Brake quality, cable length and rim type have a lot to do with optimal braking performance as well.
Figure 8 - Adjustment points on a disc brake
A disc brake system also has a similar set of adjustments that can be made, such as cable adjustment (point A) and pad distance (Point B). By turning the small red dial, the pads are set closer to or further away from the rim to allow for responsiveness, as well as pad wear. Unlike pad brakes, a small bit of rubbing is usually okay in a disc brake as some hardware is designed to let the pads “rest” very close to the rotor surface. A disc brake should not have any resistance when not engaged, nor should it make an annoying ring, so the pad adjuster needs to be set correctly.
Figure 9 - Removing a brake pad
Brake pads are wear parts, and need replacing when they are spent. Although I have yet to see a disc brake wear out, I have seen many rubber pad brakes worn enough to replace. As shown in Figure 9, a caliper brake pad is removed (and adjusted) by unscrewing the nut or bolt that secures the bad to the braking arm.
Figure 10 - Brake pad completely removed
On a cantilever brake system, the brake pad has a stem that seats into a cup that acts like a vice, allowing the pad to be moved in several degrees of freedom in order to adjust to the rim. A side pull brake is similar, although it only allows the pad to adjust up, down, and rotated around for rim adjustment. Many pads are interchangeable between brakes of the same type, so it is easy to swap parts if you have been collecting them.
Figure 11 - Cantilever brake studs
Cantilever brakes require a pair of studs that are welded to the frame in the proper place to allow the pads to contact the rim. These small studs can be easily cut from a frame or front fork by using a zip disc or hacksaw and then transplanted to a new frame by welding them in place. Figure 11 shows a pair of cantilever studs after removing them from the seat stays of an old bicycle frame.
Figure 12 - Improvised disc brake mounting system
A disc brake is a simple device to install, but does require a bit of care to get the caliper hardware aligned properly around the disc. I have used several “tricks” to get the brake hardware installed on various trikes and quadcycles, such as this flat-bar mounting method shown in Figure 12, which allows the brake to be locked onto the disc and then welded in place to ensure perfect alignment. It is also important to consider the tremendous load put on the disc brake and its mounting hardware when designing your own braking system. Braking forces go well beyond the drive forces that any athlete could ever hope to deliver to a wheel.
Figure 13 - Tadpole trike front wheel brake
Figure 13 shown another disc brake system adapted to one of our tadpole trikes. This mounting system uses a steel plate that is custom shaped to fit the brake hardware, and allows braking forces to be delivered through the hardware out to the steering hardware.
Figure 14 - A coaster hub with built in brake
One more type braking system that you will find on a bicycle comes in the form of a coaster hub as shown in Figure 14. Typically found on kids’ bikes and single speed cruisers, this reliable and effective braking system allows the pilot to apply brakes by simply pedaling in reverse. The breaking system is internal to the hub, which makes it highly effective and very robust for vehicles that only need a single speed. The steel arm on the opposite side of the hub from the sprocket is a torque arm that must be connected to the frame to transfer breaking forces from the rim to the frame tubing.
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