Most talk regarding bicycles is about making them go. Making them stop is pretty darn important, too.
Until fairly recently, brakes on bicycles seemed more of an afterthought; a ‘safety feature’ that seemed to rely more on hopes and prayers than on, well, physics. Today, ‘braking’ systems such as cantilever and coaster have largely gone the way of the dodo bird, making way for v-brakes and disc brakes. Most modern brakes provide ample braking power, are resilient in adverse weather and provide fine control and precision for braking and turning.
Bicycle brakes use friction applied to the wheel rim, a hub-mounted rotor (or disc) or a hub-mounted drum. Every braking system has advantages and disadvantages. In this article, we will discuss those systems that appear on bikes we deal with.
Direct-pull brakes, commonly referred to as V-brakes (Shimano’s trademark direct-pull brake), have many positive attributes, and few negative. They provide the most braking power of any rim brake. Lightweight, relatively inexpensive, and easy to maintain, they also provide sufficient clearance to accommodate most tires.
The downside? As with all rim brakes, direct-pull brakes are somewhat less effective in wet conditions. This decrease in power is smaller than with other rim brakes, and is further mitigated by the increasing prevalence of aluminum-rimmed wheels. In addition, though these brakes are relatively simple to maintain, they require maintenance and pads more frequently than most rotor- or drum-based braking systems.
Direct-pull brakes are common on most types of bicycle with flat handlebars, though are increasingly overlooked in favour of disc brake systems.
Disc brakes operate in much the same manner as motorcycle brakes: calipers squeeze the brake pads against a rotor attached to the hub of the wheel. This braking system provides strong, responsive braking, with very little slip. They are, though, more expensive and heavier and they require more expertise to maintain than direct-pull brakes.
When riding off-road in loose terrain with fat, knobby tires, the braking advantage of disc brakes is immediately apparent. For serious off-road riders, it is difficult to go back to rim brakes after feeling the extra level of control and sheer stopping power afforded by this braking system. That being said, the advantages of disc brakes don’t really translate to road riding in quite the same way: skinny tires will slip on a hard surface long before either v-brakes or disc brakes start losing power, so neither has a real safety advantage.
Originally, bicycle disc brakes were mechanical (using a cable, much like direct-pull brakes). Today, many disc brakes are hydraulic. Hydraulic brakes are very responsive, very reliable, and only marginally more expensive than mechanical disc brakes. They also don’t ‘settle in’ in the same way as mechanicals (no cables to stretch), so require less-frequent maintenance.
Dual-pivot side-pull caliper brakes, otherwise know as road brakes, are a lightweight, effective rim braking system, with some serious limitations. On a skinny racing tire, these brakes are reliable and provide all the braking power you need.
The disadvantage comes into play when you try to use these brakes on anything but the skinniest of tires. These brakes do not provide enough clearance for fatter tires, unless you make the calipers longer: longer calipers are considerably more flexible and as a result, considerably less efficient at stopping.
These brakes appear primarily on road bikes (which is fine), and on BMX bikes (which may meet minimum safety requirements, but any braking power is purely coincidental).
‘Road’ disc brakes
Mechanical disc brakes can be mounted on some drop bar, or ‘road,’ bikes. They use the same principle as disc brakes on flat bar bikes. Because of the drop bar brake levers, though, the cable-pull is less efficient. Though weaker than their flat bar cousins, ‘road’ disc brakes provide the greatest amount of stopping power available. They are, however, heavier than more common rim brake systems, and therefore considered less-than-ideal for performance riding. As a result, most racing frames are not even built to be compatible with disc brakes. They are becoming more common on drop bar touring and commuter bicycles.
The cantilever brake consists of two arms activated by a centre-pull on separate pivots, usually mounted on the frame below the wheel rim. They allowed for considerably more clearance than other centre-pull brakes, without sacrificing too much mechanical advantage. The inception of the direct-pull brake (or ‘V-brake’), has largely rendered ‘cantis’ obsolete. V-brakes provide much superior braking power, less slip in wet weather, greater ease in setup and adjustment, and similar weight and wheel clearance.
The most common modern bicycle to come equipped with cantilever brakes is the Cyclocross bike. Fewer are coming with them, though, as disc brakes were recently made legal for ‘cross racing.
The U-brake is a centre-pull caliper brake that mounts to the frame on two pivots. They have roughly the same braking power as cantilever brakes. These brakes were common on cross-country bikes before v-brakes, and later disc brakes, became the norm (off-roaders being picky about little things like stopping in a controlled manner).
The brake arms on U-brakes are low profile, making this system popular with freestyle BMX-ers, as they are less likely to snag or otherwise interfere with trick riding.
Coaster brake systems
The coaster brake is probably the oldest brake design still in modern use. It uses a drum brake system integrated into the rear hub.
The coaster brake only works on single speed or internal-gear bicycles. It can only be used as a rear brake, so has a great tendency to skid when used by itself. It also prohibits backwards pedaling, precluding the safe use of toe clips or clipless pedals. In addition, they dissipate heat poorly, so should not be used for long descents.
They are, however, conceptually simple to use (pedal forward = go; pedal backward = stop), so can be quite appropriate for young children who may lack the coordination or hand strength to manage hand brakes.
The coaster brake is sealed up inside the hub, so is not affected by weather, and is quite rugged, requiring very infrequent maintenance.