When referring to breaks on a motorcycle, I assume you mean the braking system or the brakes themselves. The most powerful brake on a motorcycle is typically the front brake, often called the front disc brake. It provides the majority of the stopping power and is responsible for the majority of the deceleration during braking.
Motorcycles are designed with a hydraulic braking system that utilizes brake discs (rotors) and calipers. When the rider squeezes the brake lever on the right handlebar, hydraulic pressure is applied to the front brake caliper, which clamps the brake pads against the brake disc. This generates friction and slows down the rotation of the wheel, leading to deceleration.
Compared to the rear brake, the front brake has a larger diameter disc, a larger caliper with more pistons, and a greater mechanical advantage. These design features result in higher stopping power for the front brake. Additionally, during braking, weight transfers to the front of the motorcycle, further increasing traction and effectiveness of the front brake.
It's important to note that using the brakes appropriately and applying the right amount of pressure to each brake is crucial for safe and effective braking. Most motorcycles have a balanced braking system, and applying both the front and rear brakes in a coordinated manner provides optimal braking performance and stability.