Disc Brakes vs Rim Brakes
In recent years, disc brakes have seen widespread adoption in all categories of bikes, especially road bikes where rim brakes have reigned king for over a century, compared to the mountain bike world where disc brakes have long been standard equipment.
While disc brakes offer various advantages over rim brakes, rim brakes still do have their applications and ways in which they excel. In this article we offer a concise comparison between both types of brakes.
How do rim brakes work?
Rim brakes systems have calipers that sit over the rim/tire, and their brake pads apply force to the outer edge of the rim on a special braking surface to generate stopping power.
Advantages of rim brakes
- They’re light: this is one of the main arguments in favor of rim brakes on road bikes. High-end rim brake systems are significantly lighter than their road bike disc brake systems. In road racing or hill climb competitions, a light bike matters, and even minor weight savings give a competitive edge.
- They’re easier to service and repair: rim brake systems are very mechanically simple compared to disc brakes. Visual inspection of all components of the brake system is easy, as there are no components hidden inside closed calipers as you’ll find on disc brakes. Once calipers are centered over the rims, cable tension is adjusted and wheels are running true, a rim brake system functions as it should. With disc brakes, there are more points of potential failure, and disc brake setup, diagnosis and repair are often more challenging for the amateur home mechanic.
- They’re more aerodynamic: like weight-savings, aerodynamic efficiency matters to road racers and time trialists. If you research the topic, you will find many articles and tests on the topic, and the fundamental fact is that rim brakes have less aerodynamic drag than disc brakes. The differences are rather minor and will not really mean much to recreational riders, though, who would be better served with the boost in braking power with discs.
- Rim brakes are cheaper: While some high-end rim brake systems do cost a fair bit of money, a reliable entry level set of rim brakes will offer very acceptable performance without breaking the bank. Compared to disc brake systems, rim brakes are generally significantly cheaper.
Disadvantages of rim brakes
- Suboptimal power: Rim brakes will offer decent stopping power, but they won’t match the power offered by a good set of disc brakes, especially hydraulic systems.
- Lacking in modulation: Rim brakes can feel a bit “on/off”, and lack the modulation offered by modern disc brakes which allows for sharper bike handling.
- Rim wear: braking surfaces wear out with use. When the rim is the braking surface, this means that there will come a time when you must replace it. With fancy carbon fiber rims, this can mean an expensive component replacement (compared to just replacing a cheap component like disc rotor).
How do disc brakes work?
Disc brakes move the braking surface from the outer edge of the rim to a disc rotor located in the center of the wheel. A brake caliper sits on the rotor, and the brake pads apply friction to the rotor when the piston on which they sit is actuated by means of cable pull (in case of mechanical disc brakes) or hydraulic pressure (in hydraulic disc brakes).
Advantages of disc brakes
- Superior braking power: the best rim brakes cannot match for the boost in stopping power offered by modern hydraulic disc brakes.
- They have better thermal management: on long high-speed descents, brake components experience heat buildup. Because disc brakes utilize a rotor, not the rim, heat buildup does not compromise the rim itself.
- They offer better modulation and more precise brake control.
- They open possibilities for using wider rims because the size of the rim/tire is not limited to the limit that a rim brake caliper would accommodate.
- They’re modular and customizable: disc brake systems allow you to have larger rotors for increased stopping power and heat dissipation, or smaller ones for lighter weight. The braking surface is also not dependent on a perfectly true wheel as it is with rim brakes.
- They’re better suited to riding in adverse conditions/ Brake surfaces are not subject to much contamination from road grit as they are with rim brakes.
Disadvantages of disc brakes
- They’re difficult to service and repair. Hydraulic brake bleeding is messier, more time consuming and requires more tools than standard cable replacement and adjustment on rim brakes.
- They’re expensive.
- They come with a weight penalty compared to rim brakes.
Which type of brakes is right for you?
Disc brakes have already overtaken rim brakes on most bikes, with the exception being superlight time trial and hill climb road bikes. If you already own a bike with rim brakes and they function well, there is no immediate need to switch to disc brakes unless you find them lacking in power for where you ride.
If you’re in the market for a new bike, chances are most of your options will come specced with discs, and this is certainly a good thing unless you are in that small group of riders who are looking for a featherlight and very aerodynamic bike. Ultimately, the choice will come down to your riding style, component preferences and budget.