Bike brakes explained: disc brakes vs rim brakes vs V-brakes / Titulares de Bicicletas

Modern braking for bikes is dominated by three systems: the disc brake, the caliper rim brake and the V-brake.

The hydraulic disc brake is rapidly taking over, with its widespread adoption on road bikes following the much earlier swap to discs on mountain bikes.

That increasingly leaves caliper rim brakes and V-brakes as the domain of cheaper bikes, although some top-tier road teams outside of the WorldTour still race on rim brakes.

Here’s everything you need to know about bike brakes, including the different types of brakes available, how they work, and a short history of every brake that has ever existed.

What brakes does your bike have?

The majority of new bikes, whether that’s road bikes, mountain bikes or hybrid bikes, now use disc brakes that operate by pushing pads housed in a caliper against a brake rotor attached to the wheels’ hubs. We’ll go into different types of disc brake below.

Over the past five years, road disc brakes have rapidly taken over from rim brakes, which push brake pads against the wheel’s rim. There are good reasons for that, mainly related to more efficient and consistent stopping, whatever the weather.

On that note, and as we mentioned at the top, mountain bike disc brakes have been commonplace at all levels for years, providing powerful stopping power uninfluenced by trail conditions.

Disc brakes and caliper rim brakes take the lion’s share of braking duties across most bikes, but you’ll also find V-brakes on some cheaper urban or commuting bikes.

These also work on the rim and are attached to frame bosses on either side of the wheel. V-brakes (also known as direct-pull cantilever brakes) are operated via a cable that runs from one side of the brake and across the top, pulling the two halves together.

There are other brake designs out there, but they’re a rarity on mainstream bikes. Still, we’ll give you a full rundown at the end of this article.

Anatomy of a bike brake

Almost all bike brakes are operated using a lever mounted on the handlebars.

On bikes with a flat handlebar, including mountain bikes, there’s usually a brake lever separate from the bike’s gear shift levers.

Drop-bar road bikes and gravel bikes usually combine the brake lever and gear shifter into one unit (with separate units for the front and rear brakes), although older bikes had separate shifters on the down tube, and you can sometimes see shifters at the ends of the bars.

Single-chainring groupsets (known as 1x, or ‘one-by’) will have one brake lever with a gear shifter built-in, while the other lever will only work as a brake.

Singlespeed bikes have levers that just operate the brakes, as there are no gears to operate.

When you operate the brake lever, either it pulls a cable or pushes hydraulic fluid through a hose. In either case, there’s a physical line to the brake caliper from the lever.

We’ll explain the differences between how rim and disc brakes work in detail below, but in both cases, applying the brakes pushes pads against a braking surface to generate friction and heat to slow or stop the bike.

How do disc brakes work?

In a disc brake, the brake pads are housed in a caliper bolted to the frame.

The front brake caliper is attached to the left fork blade and the rear brake usually to the left chainstay, but occasionally to the left seatstay or between the two. They house brake pads that act on a rotor attached to the wheel’s hub, pressing against this to slow the bike.

The brake caliper is either mounted on posts protruding from the bike’s frame (usually found on mountain bikes). This standard is referred to as post-mount.

Flat-mount is an evolution of this and sees the caliper bolted to a designated flat surface on the frame (the default system now used on road bikes, gravel bikes and some cross-country mountain bikes).

Disc brake pads are typically made from an organic, sintered or semi-metallic compound, each with its own advantages and disadvantages depending on the type of riding you’re doing.

Disc brake rotors

The disc brake rotor is usually made of steel and sized between 140mm and 203mm in diameter, with larger rotors used where stronger braking is needed, such as on downhill mountain bikes.

The rotor may be connected to the wheel hub with either six bolts or using Shimano’s Centerlock system, where a lockring screws onto threads in the hub.

Centerlock is seen on the majority of road bike wheels. The lockring is usually threaded on its inside face and tightened with a cassette lockring tool.

You can also buy externally flanged lockrings, which tighten with a bottom bracket cup tool. Some wheels need an externally flanged lockring because the axle is too wide for a tool to fit on an internal flange.

One potential issue with disc brakes is that the rotor can get quite hot when in use. This can lower braking efficiency and also cause the rotor to warp.

Brake manufacturers try to get around this in a few ways; first, rotors and pads may include cooling fins to help lower their operating temperature. It’s the method used by Shimano in its road and mountain bike rotors.

Second, rather than being made in one piece, the rotor may be ‘floating’. This is where the braking surface is riveted to a carrier spider that bolts to the wheel hub. When it heats up, a floating rotor should expand more evenly than a solid rotor and so is less likely to distort. The float also helps even out pressure between the pads acting on the two sides of the rotor.

Finally, rotors may be made of a sandwich of steel with an aluminium core, which again helps with heat dissipation and also reduces weight.

Hydraulic disc brakes

In a hydraulic disc brake, a piston in the brake lever pushes hydraulic fluid through the brake hose when the brake is applied. The fluid pushes the brake pads together and against the brake rotor. When the brake is released, a spring pushes the pads away from the rotor and back into their housings.

Hydraulic disc brakes will work efficiently with convoluted hose runs from the brake levers to the brakes, so they are a good option for triathlon and time trial bikes with internal hose routing.

Most hydraulic disc brakes have one piston on each side of the rotor, but disc brakes designed for downhill riding often have a total of four pistons to allow more braking force to be applied.

Disc brakes use a wide variety of pad designs and shapes. If you’re replacing your pads, you need to be careful that your new ones will fit your brake caliper.

Hydraulic disc brakes have the advantage that there’s no friction in the hose and so all your braking effort is transmitted to the brake.

As the hydraulic line is a closed system, there’s less maintenance required than a cable-operated brake, though the system may need bleeding occasionally if it gets contaminated. Learning how to bleed brakes is a key skill for any committed home mechanic.

The pads will also need to be replaced when they get worn or contaminated with oil or other substances, which reduce braking efficiency.

Different brands use different hydraulic fluids in their brakes. It’s important to use the right one if you need to bleed the brakes, to avoid damage and possible failure of your equipment’s seals. Boiling the brake fluid is potentially a problem with prolonged, hard braking as well.

Cable disc brakes

In a cable-operated disc brake, the physical connection between the lever and the brake caliper is made with a wire cable.

The cable pulls a lever on the caliper, which usually pushes a pad on each side of the caliper into contact with the rotor. SRAM’s Avid cable-operated disc brakes only move the outboard brake pad. The rotor pushes against a static inboard pad.

Hydraulic disc brakes vs cable disc brakes

Due to the frictional loss and stretch in the cable, cable-operated disc brakes lose out to hydraulics both in out-and-out braking force and modulation, but the best models are still more efficient than the majority of rim brakes.

Cable disc brakes are a cheaper option than hydraulic brakes, so are often found on lower-spec bikes, and are easier to fix out in the wilds.

However, most mid-to-high-end bikes with disc brakes will have a hydraulic system for good reason.

Rim brakes

Side-pull caliper brakes were the primary choice for road bikes for decades.

They’re lightweight and can provide strong braking, although they’re much more susceptible to performance degradation in the wet than disc brakes.

Braking performance can be degraded on carbon rims in the wet too, and there’s a risk of overheating with prolonged braking on carbon brake tracks.

It’s for those reasons, plus the opportunity to fit wider road bike tyres and to make carbon rims lighter if they’re not used for braking duties, that modern road machines have moved substantially to disc brakes.

That said, a pair of well set-up rim brakes on alloy rims are more than sufficient for nearly all riders. Bikes equipped with rim brakes are also usually significantly cheaper than their disc equivalents, even if they’re hard to come by on the latest releases.

There’s a wide variety of different caliper brake designs out there, and we’ve explained some of the more common types below.

Single-pivot caliper brakes

In days gone past, single-pivot caliper rim brakes were the norm.

With these, both arms rotated around a single, centred pivot, which theoretically allowed the brake to self-centre and track an out-of-true rim more effectively than a dual-pivot brake. These brakes were attached via a single bolt in the fork crown and the rear brake bridge.

Centre-pull brakes were the norm in the peloton (more on these later) until the introduction of the legendary Campagnolo Record sidepull brake in the early 1960s, which was both lighter and nearly as powerful as the centre-pull design.

Side-pull brakes quickly became favoured by the pros and, with roadies of the past just as keen to imitate the peloton as today’s riders, the…