Stopping Short: The Brakes

In This Chapter

^ Identifying the different types of brakes ^ Removing and installing brakes and brake pads ^ Adjusting your brakes ^ Addressing brake issues

hen Dennis was a kid, one of his bikes had a braking system that required him to use his foot to stop the pedals and cranks from rotat­ing forward in order to come to a halt. The advantage of this design was that he could look cool by skidding out when he needed to stop the bike.

Somewhere between then and now, skidding out has lost its appeal, and odds are, you’re less concerned with impressing your friends than you are with stopping safely. Fortunately, today’s bikes have braking systems that can consistently stop the momentum of the bike and the rider’s weight with little more than a firm squeeze of the brake levers.

Although brakes designs have evolved to be highly reliable when it comes to stopping a bike, this doesn’t mean that you should take them for granted. Proper maintenance and inspection of your brakes will increase the chances that, if you round that next turn too fast or if someone backs his car out in front of you without looking, you won’t have to make one giant skid mark.

We start this chapter with a quick overview of the different types of brakes on the market today. Then we narrow our discussion, focusing on the most popular type of brakes — rim brakes — and the various styles of rim brakes. We tell you how to remove and install brakes and brake pads, make adjust­ments to your brakes, and address common braking issues.

120 Part II: Basic Bike Repairs__________

Types of Brakes

There are three major categories of braking systems on modern bikes:

✓ Rim brakes: When you squeeze the brake levers of rim brakes, the brake cables pull on one or both brake arms, which causes the rubber brake pads to come in contact with the wheel rims and slow the bike down. The ben­efits of rim brakes are that they’re cheap and relatively easy to maintain, and they have a lot of stopping force. The drawback is that they don’t work well in wet or muddy conditions and they can wear out quickly.

The three popular models of rim brakes are:

• Cantilever brakes: Cantilever brakes (see Figure 8-1) have short, L-shaped brake arms that bolt to the frame and are connected by a straddle cable, which looks like an upside-down Y. They’re mounted on two pivots, one on each side of the wheel. The pivots (bosses) are set close to the wheel, which increases their mechanical advan­tage. Cantilever brakes have very good braking power. They’re com­monly found on road bikes, mountain bikes, and touring bikes.

• V-brakes: V-brakes (see Figure 8-2) are sometimes referred to as linear-pull or direct-pull brakes. The brake arms are at nearly a 90-degree angle to the brake pads. V-brakes are mounted on two pivots on the frame, one on each side of the wheel. The longer arms give V-brakes improved leverage and greater stopping power. They’re commonly found on mountain bikes and hybrid bikes.

• Center-mount brakes: With center-mount brakes (see Figure 8-3), the brake cable attaches to one of the brake arms. The brake arms are together as one unit and mounted to a single pivot, which sits above the wheel. (In the double-pivot variety, there are two pivots — one on each side of the wheel — but still only one center mounting bolt.) The brake pads are at the bottom of the arms. Center-mount brakes don’t provide as much power as V-brakes

or cantilevers. They’re commonly found on road bikes and lower — price bikes.

✓ Disk brakes: Squeezing the brake levers on disc brakes (see Figure 8-4) causes the brake pads to squeeze against a metal disc that surrounds the hub. There are two main types of disc brakes — mechanical and hydraulic. Mechanical disc brakes utilize a cable to actuate the brake pads, whereas hydraulic brakes use a brake fluid pushed down by a piston through a brake line to generate braking power. Both types work well in both dry and wet conditions, and they’re quite responsive, requiring less effort from the hand when breaking. The advantage of disk

brakes is they don’t heat up the rim on long descents, causing the tire pressure to increase and possibly blow out. Also, they don’t wear out the sidewall of a thin and lightweight alloy rim. The disadvantage of disk brakes is that they’re usually heavier, cost more, and require a hub that can accept a disk. Disk brakes are commonly found on mountain bikes.

✓ Hub brakes: Sometimes called drum brakes, hub brakes are similar to disk brakes except the brake pads are pushed outward against the inside of a cylindrical drum inside the hub. The fact that they’re on the inside of the hub means they aren’t affected by wet, muddy, or dusty conditions. However, they are the heaviest of all the brakes. They’re found on some tandem bikes.