Disc vs Drum-Brake systems explained


In a country with high frequency of accidents such as India, safe riding is a major concern. Brakes play a major role in the safety system of a motorcycle. Manufacturers these days are launching bikes with front disc brakes as standard. However, this article will serve as a jargon buster. Are disc brakes superior to drum brakes? If so, then how? Should all bikes have disc brakes at both wheels? Read on to find out

Principles involved                       

To compare and contrast disc brakes and drum brakes, it is necessary to get an idea of the underlying principles involved. A brake is a retardation device which converts energy from one form to another. Here, the kinetic energy of the moving wheels is converted into heat energy by means of friction between the brake pad and contact surface. A brake’s efficiency is determined by its ability to convert kinetic energy to heat energy and also by the rate at which this heat is dissipated. Now, that key concept is understood, let’s look at the two brake systems.

Drum Brakes Explained


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Drum brakes, as the name suggests are in the shape of a drum. This drum moves along with the vehicle’s wheels. The main components of the drum brake are brake pads and piston. When the brakes are applied, brake fluid forces the piston to push the brake shoes outwards against the spinning drum. The friction causes the vehicle to come to a stop.

Disc Brakes Explained


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Disc brakes have a rotating disc which rotates along with the wheel. Brake pads are present on both sides of the disc, which when pressed against the brake, forces the vehicle to come to a stop. When the brake pedal is applied, brake fluid pressure forces the piston to press the brake pads against the disc. Conversion of energy takes place and the vehicle comes to a stop. The Disc is usually provided with vent holes which allow heat to dissipate quickly.

Disc Brakes vs. Drum Brakes

Look at the last point under disc brakes. Vents present on the disc improve the heat dissipation rate. Also, they are exposed to air whereas the drums are not. In a vehicle equipped with drum brakes, excessive friction causes a surge in temperature due to which the drum expands outward. Because of this, more effort has to be exerted to bring the vehicle to a stop. Like I said in the previous section, heat dissipation rate is directly proportional to efficiency of the brake. Another disadvantage of drum brakes is that they are pretty useless when exposed to water.

In a nutshell, Disc brakes are easier to inspect, have fewer parts, have a superior design and better stopping power. The only advantage Drum brakes have is that they are cheaper to manufacture.

Conclusion-The Current Scenario

Like I said before, these days, most manufacturers are providing front disc brakes as standard in their new products. But most of the bikes continue to employ drum brakes at the rear. Is this a bad thing?

The answer is no. As the years have gone by, drum brake technology has also improved so much that some of them are more efficient than disc brakes of yesteryear. Also, during braking, due to mass transfer, most braking effort is needed at the front wheels. Most of the entry level bikes do not require a rear disc brake. Using a disc will also increase the costs on all these bikes. Thus, although a front disc brake is absolutely necessary, a rear disc brake is not so critical.



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