Should I use disc brakes or rim brakes?

Differences Between Disc Brakes and Rim Brakes

Both Work on the Same Principle of “Clamping to Brake”

While disc brakes and rim brakes may seem very different, they actually operate on the same principle of “clamping to brake.”

Traditional rim brakes such as caliper brakes and V-brakes clamp the rim of the wheel to brake, whereas disc brakes clamp a rotor attached to the wheel hub. However, both systems work by “clamping to brake,” making the fundamental mechanism the same.

Thus, the key difference is the location of the clamping, which, while subtle, results in significant differences in performance.

Differences in Braking Power

It is often said that “disc brakes have more stopping power than rim brakes,” but a more accurate statement is: “With hydraulic disc brakes, finer and stronger braking can be achieved compared to rim brakes.”

In terms of stopping power, V-brakes are quite powerful, and caliper brakes at higher grades also offer sufficient stopping power.

The difference comes in the initial application of the brakes. Hydraulic disc brakes start braking effectively from the moment the lever is pulled, while V-brakes and caliper brakes typically start braking effectively when the lever is pulled about 60-80% of the way.

This difference is the basis for the perception that “disc brakes work better.” While disc brakes certainly have their advantages, much of this comes down to the hydraulic aspect.

By the way, mechanical disc brakes, which are less precise in adjustment, are sometimes said to offer lower braking power than higher-grade rim brakes. However, high-performance mechanical disc brakes, like those in GROWTAC’s EQUAL series, have been developed to offer braking power comparable to hydraulic disc brakes.

Difference in Braking Power in Wet Conditions

The strength of disc brakes lies in their resistance to water, sand, and other contaminants.

In wet conditions, such as rain, rim brakes can experience a decrease in braking power. Water or sand can stick to the rim, reducing the coefficient of friction between the brake pads and the rim, leading to a drop in braking performance. This is because the rim is close to the road surface, and this cannot be avoided. In particular, for carbon rims, without using high-end carbon-specific brake pads, some cyclists feel that “the brakes barely work on rainy days.”

On the other hand, disc brakes are less affected by weather conditions because the disc rotor, which is clamped, is attached to the wheel hub, meaning the braking surface is distanced from the road. As a result, disc brakes are less influenced by road conditions, leading to less reduction in braking power in wet or muddy conditions.

Since road bikes are all-weather vehicles, cyclists sometimes ride in the rain. Especially for professionals, it’s not an option to skip races just because it’s raining, so choosing disc brakes that maintain braking power in wet conditions is a given.

Pros and Cons of Disc Brakes vs. Rim Brakes

Now, let’s compare the pros and cons of each brake type.

From this comparison, it becomes clear that disc brakes are not always the perfect solution.

In fact, some professional road cyclists prefer rim brakes, and the UCI WorldTour team Ineos Grenadiers, while many competing teams switched to disc brakes, continued to use rim brake bikes in actual races until mid-2021, citing that “the weight of disc brake bikes did not meet the team’s required level (they were too heavy).”

The Trend of the Times: “Hydraulic Disc Brakes”

From Lightweight Wheels to “Lightweight and Aero Wheels”

In the past, road bikes were commonly known for their “narrow rims and light weight,” but today, the trend is shifting towards “aero wheels” with high rim heights and superior aerodynamics, especially in road bikes.

Historically, in bicycle wheels, it was common knowledge that “deep-rim aero wheels = heavy” with metal rims. Due to weight concerns, aero wheels with high rim heights were typically avoided except in time trials. However, with advances in carbon fiber technology, it is now possible to make even deep-rim wheels lightweight by using carbon materials.

The focus on aerodynamics in cycling now extends beyond just frames and wheels to handlebars and helmets, becoming one of the key factors when choosing a bike.

Addressing the Heat Sensitivity of Carbon Rims

The rims, which are essential parts of a bicycle wheel, are typically made of three main materials:

1. Steel
2. Aluminum
3. Carbon

In recent years, the trend in high-performance bikes, especially road bikes, has been towards weight reduction, making it necessary to lighten components like the wheel rims, which contribute significantly to the bike’s overall weight.

In this context, carbon materials have become increasingly popular, particularly for higher-end wheels. While carbon is lighter than metal, it is more heat-sensitive. In rim brakes, which apply pressure to the rim to create friction, the heat generated by braking can deform or damage the rim.

This is where disc brakes have gained attention. Since disc brakes use a metal rotor for braking, the material of the rim has no impact on braking performance. This allows for both “lightweight carbon rims” and “prevention of rim deformation” to be achieved, leading to the industry’s shift toward disc brakes.

As a result, we are now in the era of hydraulic disc road bikes, with all high-end models from major road bike manufacturers now equipped with hydraulic disc brakes.

Is the End Near for Rim Brakes?

Rim Brakes Are Still Usable

So, is it true that “rim brakes are over”? Not quite. There are still plenty of rim brake models available in entry-level to mid-range road bikes priced under 200,000 yen. For the next few years, rim brake models will likely coexist with disc brake models.

In fact, even after the “wave of disc brakes” started to rise in 2022, some major manufacturers have continued to produce road bikes with rim brakes.

Also, considering the used market, users who have switched to disc brakes may start releasing their rim brake assets (wheels, components, etc.), so the next few years may see an abundance of used rim brake options in the market.

Given this, rim brakes will likely remain the main option for the next 5 years. Eventually, the prices of disc brake complete bikes and parts will stabilize, so switching to them later won’t be an issue.

However, new rim brake models will likely become rarer in the future, leading to a decrease in the stock of new bikes. If you’re planning to use a rim brake bike for a while, it might be a good idea to purchase high-quality rim brake components and wheels within the next 1-2 years.

Understand that Upgrading from Rim Brakes to Disc Brakes is Generally Not Possible

It’s important to understand that upgrading from rim brakes to disc brakes is generally not feasible.

To install disc brakes on a bike, the following four requirements must be met:

1. Disc brake-compatible wheels
2. A frame and fork with disc brake caliper mounts
3. A frame and fork with compatible end widths for disc brake wheels
4. A wheel-specific mounting system (quick release / thru-axle)

The biggest issue is with the rear end, as rim brake bikes typically have 130mm or 135mm quick-release dropouts, while most disc brake wheels use 142mm thru-axles (though some older bikes or 135mm quick-release disc frames exist). This means it is physically impossible to mount disc wheels on a rim brake bike.

This is one of the drawbacks of buying a rim brake bike at this point, so when purchasing, you may want to consider how long you’ll continue using that bike.