Brake technology has come a long way since its beginnings. Motorized vehicles have gradually started to travel at higher speeds and passenger safety has become very closely tied to the ability to decelerate quickly and efficiently.
This brings up the different brake systems: Which is better drum or disk brakes?
To understand the differences between drum and disc brake technology, we must first outline the physical forces necessary to bring a vehicle to a complete stop.
Brake Friction And Heat
All brake technology is based on the simple properties of friction. When a load is applied between two objects that make contact, a resisting force is produced. This force converts kinetic energy to thermal energy and parameters like amount of load applied, surface area and surface roughness influence the force of friction.
In brake systems, a force is applied between a brake lining (pads or shoes) and a braking surface (rotor discs or drums), while creating heat as a byproduct. How quickly a brake system can decelerate a vehicle is directly dependent on the force applied between the braking surfaces and the total braking surface area (well, also vehicle weight, brake materials, incline, but we won’t consider all of those). But what cannot be overlooked is the efficiency of how brake systems dissipate heat because all kinetic energy removed by braking is directly converted into heat.
Overview of Drum Brakes
Most early brake systems started out using drum brake technology. Drum brakes are cheaper and simpler to manufacture and rely on a set of shoes that apply force outward onto an enclosing cylinder, called a drum.
There are few limitation of drum brakes: their brake force, brake lining and brake surface are very similar to that of disc brakes. However, a major difference comes in the way of heat dissipation. Since the drum encloses the brake shoes inside, heat is trapped within the drums. Instead of having a constant stream of air cooling, drum brakes build up heat inside and can even suffer from heat saturation that greatly hinders their stopping ability after their maximum heat threshold is exceeded. This generally happens only on long mountain descends and race tracks, so there is a reason that most performance vehicles opt for disc brakes for their superior cooling ability.
Advantages of Drum Brakes
- Simpler Design
- Cheaper to manufacture
- Less prone to external debris
Disadvantages of Drum Brakes
- Worse heat dissipation
- Prone to heat saturation (resulting in losing ability to stop)
- Harder to maintain (due to rusting)
Overview of Disc Brakes
Disc brakes are quickly becoming the standard for both the automotive and bicycle industry. They work by using a caliper with pads that clamps down on a rotor disc that is rigidly fixed to the wheel.
Their superior responsiveness and heat dissipation make them a clearly better choice over drum brakes. Because the rotor discs are exposed to oncoming air as the vehicle moves, the brakes are always kept cool without excess heat buildup. Tighter tolerances and larger brake surfaces allow for better stopping power that is available faster as you engage the brakes. There are clear reasons why disc brake technology has been widely adopted as the new standard across all transportation industries.
Advantages of Disc Brakes
- More responsive
- Better heat dissipation (due to air flow cooling)
- Easier maintenance
Disadvantages of Disc Brakes
- More expensive to produce
- Rotors discs may warp after repeated exposure to high heat
On the CycleBoard
The CycleBoard uses a rear vented disk brake to give you superior precision and control. With the same technology that’s used on high-end mountain bikes, you know you will always be able to stop – even if there is a sudden loss of electrical power. Built from the highest quality materials, the rotor and caliper are extensively tested by our engineering team and are guaranteed to exceed your expectations from day one.