Why can't the rear disc brake of a motorcycle stop the vehicle?
2 Answers
Motorcycle rear disc brakes failing to stop the vehicle may be caused by a lack of brake fluid or damage to the oil pump. Here is the relevant content introduction: 1. Disc brakes: Disc brakes consist of a brake disc connected to the wheel and a brake caliper at the edge of the disc. When braking, high-pressure brake fluid pushes the brake pads to clamp the brake disc, thereby generating a braking effect. 2. Classification: Disc brakes are sometimes also called disk brakes, which are divided into ordinary disk brakes and ventilated disk brakes. Ventilated disk brakes have many round ventilation holes drilled on the disc surface. The main advantages of disc brakes are the ability to brake quickly during high-speed braking, better heat dissipation than drum brakes, stable braking performance, and ease of installing advanced electronic equipment such as ABS.
I've been riding motorcycles for over ten years and have encountered several instances where the rear disc brakes failed to stop properly, each time posing a significant danger. The most common issue is severely worn brake pads, where the metal backing is exposed or contaminated with grease and dust, leading to insufficient friction. Another problem is uneven brake discs or contamination with water or oil, where a light squeeze of the brake lever yields no response, requiring a hard pull to feel any braking effect. Additionally, brake fluid can degrade or develop air bubbles in the system, especially if air isn't fully bled after a fluid change, resulting in a spongy, ineffective brake feel. I recall one long-distance ride where the rear brake suddenly failed, and I discovered the brake fluid level was critically low due to a system leak—that was a close call. For regular maintenance, I recommend checking brake pad thickness periodically and not waiting until they're completely worn out. Avoid spraying water directly onto the brake components when washing the bike to prevent water contamination. If the brakes feel soft, get them serviced immediately—don't risk riding further to save time. Brake issues are a major safety hazard that can be life-threatening, so never delay addressing them.
