Mountain bikes are increasingly using disc brakes and for good reason. They provide greater stopping ability in all settings. So why are disc brakes not used on road bikes?
There are several reasons for this, including weight, aerodynamics, and compatibility. Disc brakes add more weight, are less aerodynamic, and are generally incompatible with road bikes. All of this defeats the main purpose of the road bike, i.e., speed and efficiency.
Let’s take a closer look at each of these reasons.
What Exactly Are Disc Brakes?
Conventional rim brake calipers work by squeezing a rubber-based brake pad against the wheel rim, generally with the help of a brake wire that extends from the lever. The front and rear calipers are directly affixed to the top of the fork, and a bridge between the rear seat stays, respectively.
Meanwhile, disc brakes use calipers that clamp onto special braking rotors—steel discs—mounted to the front and rear hubs.
Pistons that are either hydraulically or cable-actuated will force the brake pads together. Although disc brakes have been a part of vehicles and motorcycles since the early 1900s, they are relatively new to road cycling.
Check out this video below to understand the difference between disc and rim brakes:
Why Do Road bikes Not Use Disc Brakes
We’ve listed the main reasons why road bikes do not use disc brakes.
While road riders do all they can to keep their bikes as lightweight as possible for speed purposes, disc brakes will add weight to the bike. Rim brakes are often lighter than disc brakes, particularly hydraulic disc brake systems.
The weight of a disc brake system is increased by the weight of the levers, braking caliper, hoses, fluid, and rotors. Manufacturers frequently make an effort to minimize the difference but keep in mind that disc brake hubs are also heavier and that disc brake wheels are frequently constructed with more spokes of a wider gauge.
However, disc-specific rims are typically lighter due to the absence of a brake track. Most disc systems have through axles, which are heavier than fast-release skewers. The weight difference isn’t significant, but when everything is considered, it may typically be approximately one pound over the entire bike.
Aerodynamics Road riders must also take aerodynamics into account. Disc brakes impact aerodynamics, just like any other exterior component. It’s not as easy as declaring that rim brakes are always more aerodynamic, despite some manufacturers claiming that a certain bike’s rim brake version is more aerodynamically effective than the disc brake version.
Compatibility is another critical element. Hub, wheel, and frame modifications are necessary for disc brakes. This might make it challenging to update your bike and obtain new parts.
Incompatible With Purpose
Road bikes are made as light and quick as possible, making them perfect for long-distance and competitive riding. Road bikes do not have disc brakes and for a good reason.
As they provide better-stopping force and are less influenced by weather conditions, disc brakes are becoming more common on all sorts of bicycles. They may, however, slow you down because they add weight and drag to the bike, especially on steep hills.
If you want a quick, effective road bike, go for one without disc brakes.
Because they are sealed, disc brakes shouldn’t require much regular maintenance, but when anything goes wrong, it may be more challenging to fix. When an air bubble becomes stuck in the system, disc brakes occasionally need to be “bled,” which is more difficult than, for instance, correcting a caliper rim brake.
Additionally, compared to rim brake systems, disc brake systems require more frequent brake pad replacements. Consequently, keeping disc brakes in excellent operating order takes more time and effort.
Due to the reduced width of the tires on road bikes, disc brakes might become problematic when used on road bikes. The friction between the calipers and the tires can reduce performance and cause wear and tear.
The calipers may possibly sustain damage in rare circumstances. So, before installing disc brakes on a road bike, it’s crucial to speak with a professional. Doing this allows you to keep your bike operating at its peak performance and prevent any possible issues.
Disc brakes could also cost more money. Rim brakes are comparatively straightforward and affordable and function by pushing pads against the wheel rims. While hybrid and completely hydraulic disc brake calipers will cost more to buy, mechanical disc brake calipers do not significantly differ from their similar rim-brake counterparts.
When compared with changing brake cables or rim brake pads, hydraulic disc brake service takes longer and costs more.
On the other hand, the components’ extended lifespan makes them potentially more cost-effective long-term purchases and less wasteful overall. After the initial purchase expense, the brake pads also often last longer than rim brake pads, and when the rotor wears out, it can easily be changed at a considerably lower cost than changing the complete rim of a rim brake wheel.
Why Do Professionals Prefer Rim Brakes?
The great majority of riders in the elite ranks still use rim brakes. This is a result of their decreased weight and improved aerodynamics.
Additionally, rim brake-equipped bike manufacturers sponsor most professional riders, giving them a better understanding of the equipment and faster access to parts and assistance.
Even though disc brakes are gaining popularity among professionals, they are not yet the standard. As disc brakes become lighter and more aerodynamic, this will probably change. But for now, rim brakes continue to be preferred by the majority of professionals.
In conclusion, disc brakes are not featured on road bikes due to their weight, decreased aerodynamics, and increased maintenance requirements. The choice of brakes is essentially a matter of personal preference.
Some riders are content with disc brakes and are unlikely to switch at any point. A rim brake is typically more than capable of providing you with the braking you need. Because they are lightweight, a rider seeking those slight advantages is unlikely to prefer the disc brakes’ added weight disadvantage. When switching, be sure to speak with a bike mechanic to avoid any possible issues.