Hydraulic disc brakes have transformed modern cycling. Whether you ride downhill, enduro, full-power e-MTB, gravel, road or commuter bikes, hydraulic brakes allow riders to brake later, control speed more precisely and manage steeper terrain with far more confidence than older cable systems.

But hydraulic brakes are often misunderstood. Brake pads do not create hydraulic power on their own. The hydraulic system creates the clamping force, while the pads control how that power is applied through friction, heat behaviour, feel, noise and consistency.

How Hydraulic Disc Brakes Work

A hydraulic brake works by transferring force through an incompressible fluid. When you pull the brake lever, a piston inside the master cylinder moves fluid through the brake hose towards the caliper.

That pressure moves the caliper pistons, pushing the brake pads into the rotor. The friction between the pad compound and rotor slows the wheel down.

The hydraulic system creates the force. The pads control how that force feels and behaves.

Main Parts of a Hydraulic Brake

What Actually Creates Brake Power?

Brake power comes from the complete brake system, not one individual component.

• Lever leverage ratio
• Master cylinder piston size
• Caliper piston area
• Rotor diameter
• Rotor thickness and thermal mass
• Pad compound friction coefficient
• Caliper stiffness
• Brake hose expansion
• Bleed quality and fluid condition

This is why two brakes using the same pads can feel completely different. A powerful hydraulic system with a poor pad compound can still feel inconsistent, while great pads cannot fully compensate for a contaminated or poorly bled brake.

Understanding Lever Stroke

Open Systems and Compensation Ports

Almost all modern hydraulic bicycle brakes use an open system with a reservoir or bladder to compensate for fluid expansion, temperature changes and pad wear.

The compensation port is critical. It allows the system to equalise when the brake is released. Once the lever is pulled and the port closes, hydraulic pressure can build.

If the port closes too late, the brake can feel vague with excessive dead stroke. If it closes too early or becomes blocked, the brake may drag or lock as the fluid expands with heat.

Caliper Pistons and Seal Rollback

Most modern MTB, e-bike, gravel and road brakes use opposed pistons, meaning pistons move from both sides of the caliper and apply pressure evenly across the rotor.

More pistons does not automatically mean more power. Total piston area, caliper stiffness, piston distribution and pad support are often more important than piston count alone.

The square-profile piston seal also helps retract the piston when the lever is released. This is known as seal rollback. Too much rollback creates a long lever throw, while too little rollback can cause brake rub.

DOT Fluid vs Mineral Oil

Never mix DOT fluid and mineral oil. The seals inside the brake are designed specifically for one type only.

Brake Pad Compounds Explained

The correct pad compound depends on riding style, terrain, rider weight, rotor size and braking temperatures.

Explore Gorilla Brakes pad ranges: Mountain Bike Brake Pads, e-Bike Brake Pads, Gravel Bike Brake Pads and Road Bike Brake Pads.

Why Bedding-In Matters

Bedding-in creates a controlled transfer layer between the brake pad and rotor. Without proper bedding-in, brakes can feel weak, noisy, inconsistent or grabby.

This is especially important when changing from one compound type to another, such as organic to sintered. The old transfer layer on the rotor may not match the new pad material.

For more setup help, visit our Installation & Maintenance page.

Brake Noise: Pads Do Not Make Noise on Their Own

Brake noise is vibration. That vibration usually comes from inconsistency somewhere within the braking system.

• Contaminated pads or rotors
• Uneven piston movement
• Poor caliper alignment
• Incorrect bedding-in
• Rotor thickness variation
• Air in the hydraulic system
• Loose hardware

Some compounds can amplify noise more than others, especially harder metallic compounds, but the root cause is usually vibration or contamination somewhere in the system.

Rotor Size, Thickness and Heat Capacity

Larger rotors increase braking torque because the braking force acts further from the wheel axle. They also improve heat management by increasing surface area and thermal mass.

Modern bicycle rotors commonly include 140mm, 160mm, 180mm, 200mm, 203mm, 220mm and 223mm sizes depending on discipline.

Rotor thickness is becoming increasingly important for downhill and full-power e-bike systems. Thicker rotors can absorb and manage more heat before temperatures spike.

Why Brakes Fade

How Green Fade Works With Sintered Brake Pads

Sintered brake pads behave differently during bedding-in compared to organic or resin compounds. Because the friction material is made from metallic particles fused together under heat and pressure, sintered pads are harder, denser and more heat resistant.

This means they usually take longer to fully bed in and establish a stable transfer layer on the rotor.

When brand-new, only small high spots on the pad may initially contact the rotor surface. Until the pad and rotor fully mate together, braking can feel:

• Noisy
• Weak
• Grabby
• Inconsistent

This is why many riders incorrectly think sintered pads are poor performers when first installed. In reality, the compound simply has not fully stabilised yet.

Why Sintered Pads Need More Bedding-In

Sintered compounds transfer heat differently from softer organic compounds. They also resist wear far more effectively, which means they do not conform to rotor imperfections as easily during the first few rides.

Until the transfer layer becomes even across the rotor surface:

• Friction can feel inconsistent
• Vibration is more likely
• Noise levels can increase
• Initial bite may feel weaker

Sintered pads often require more controlled heat cycles before reaching their full performance potential.

Why Riders Experience “Green Fade” With New Sintered Pads

A common mistake is fitting fresh sintered pads and immediately riding steep descents or dragging the brakes continuously under high heat.

This can overheat the fresh friction material before the transfer layer has stabilised, causing:

• Temporary loss of friction
• Pad glazing
• Squealing
• Rotor vibration
• Uneven transfer layers

The brake lever may still feel firm because the hydraulic system is working correctly, but the friction surface between the pad and rotor becomes unstable.

Switching From Organic to Sintered Pads

Changing from organic pads to sintered pads without cleaning the rotor properly is one of the biggest causes of brake noise and inconsistent performance.

The rotor already contains an existing transfer layer from the old compound. The new sintered material then attempts to work over incompatible friction material.

This can cause:

• Squealing
• Pulsing
• Vibration
• Poor bite
• Uneven braking feel

Best Practice for Bedding-In Sintered Pads

For best results:

1. Clean the rotor thoroughly with isopropyl alcohol
2. Lightly abrade the rotor surface if changing compounds
3. Perform gradual heat cycles
4. Avoid dragging the brake continuously during the first rides
5. Do multiple controlled hard stops
6. Allow cooling between runs

Once fully bedded in, sintered compounds usually deliver:

• Excellent heat resistance
• Strong wet-weather braking
• Long lifespan
• High fade resistance
• Consistent braking under heavy loads

This is why sintered and metallic-based compounds remain extremely popular for downhill, enduro and full-power e-MTB riding where braking systems experience very high temperatures.

Modern E-Bikes Have Changed Braking

Modern e-MTBs and heavy e-bikes place far greater demands on brakes than traditional bikes. More weight, higher average speeds and longer descents all increase heat entering the braking system.

This is why modern heavy-duty brakes are moving towards:

• Larger brake pads
• Thicker rotors
• Higher fluid volume
• Stiffer calipers
• High-temperature compounds

Shop dedicated e-Bike Brake Pads for high-load braking systems.

Road and Gravel Hydraulic Brakes

Road and gravel systems use the same hydraulic principles as MTB brakes but prioritise different characteristics such as weight, control and high-speed consistency.

Gravel riders often need smooth predictable control on loose surfaces, while road riders require confidence under heavy braking from high speed.

Explore: Gravel Bike Brake Pads and Road Bike Brake Pads.

Choosing the Right Gorilla Brakes Pads

Browse the full Gorilla Brakes Brake Pad Collection.

Final Thoughts

Hydraulic disc brakes are simple in principle but extremely detailed in practice. Power comes from the hydraulic system. Control comes from how that power is delivered.

The best brake setup is not just the most powerful one, it is the one that gives consistent friction, stable temperature behaviour, predictable lever feel and reliable performance in the conditions you actually ride.

Whether you ride MTB, downhill, enduro, e-bike, gravel, road or commute every day, choosing the correct brake pad compound helps your braking system work at its best.