Do you have a bike with a rear disc brake that isn’t working properly You’re not alone. This is a common problem, and it can be frustrating and inconvenient. But don’t worry, there’s a good chance you can fix it yourself. In this troubleshooting guide, I’ll walk you through the steps to diagnose and repair a rear disc brake that isn’t working. I’ll also provide some tips on how to prevent this problem from happening in the future.
Most Common Reasons: Bike Rear Disc Brake Not Working
Most Common Reasons: Bike Rear Disc Brake Not Working
1. Mechanical Issues
Brake pads are worn out:
This is the most common cause of a rear disc brake not working. The brake pads wear down over time and eventually need to be replaced.
Brake rotors are warped:
If the brake rotors are warped, they will not provide proper braking power. Warped rotors can be caused by excessive heat, improper braking, or a collision.
Brake fluid is low or contaminated:
Brake fluid is necessary for the brakes to work properly. If the brake fluid is low or contaminated, it can cause the brakes to not work properly.
Brake calipers are seized:
If the brake calipers are seized, they will not be able to move properly and apply the brakes. Seized calipers can be caused by dirt, rust, or corrosion.
Brake cable is frayed or broken:
If the brake cable is frayed or broken, it will not be able to apply the brakes properly.
2. Hydraulic Issues
Hydraulic fluid is low or contaminated:
Hydraulic fluid is necessary for hydraulic disc brakes to work properly. If the hydraulic fluid is low or contaminated, it can cause the brakes to not work properly.
Hydraulic lines are leaking:
If the hydraulic lines are leaking, it can cause the brakes to not work properly. Leaking lines can be caused by a damaged line, a loose fitting, or a faulty seal.
Master cylinder is faulty:
If the master cylinder is faulty, it can cause the brakes to not work properly. A faulty master cylinder can be caused by a damaged piston, a leaking seal, or a faulty valve.
3. Electrical Issues
Electrical wires are damaged or disconnected:
If the electrical wires are damaged or disconnected, it can cause the brakes to not work properly. Damaged wires can be caused by a sharp object, a pinched wire, or a loose connection.
Electrical motor is faulty:
If the electrical motor is faulty, it can cause the brakes to not work properly. A faulty motor can be caused by a damaged winding, a broken gear, or a faulty controller.
How to Troubleshoot: Bike Rear Disc Brake Not Working
Symptoms
The rear brake lever feels spongy or doesn’t return to its original position after being squeezed.
The rear brake doesn’t slow the bike down as much as it should.
The rear brake makes a squealing or grinding noise when it’s applied.
The rear brake pads are worn down to the metal backing.
The rear brake rotor is warped or damaged.
Causes
The brake fluid is low or contaminated.
The brake pads are worn out or incorrectly installed.
The brake caliper is misaligned.
The brake rotor is warped or damaged.
The brake cable is stretched or frayed.
The brake lever is damaged.
How to Fix: Bike Rear Disc Brake Not Working
1. Check the brake fluid level:
If the brake fluid level is low, add more brake fluid to the reservoir. Make sure to use the same type of brake fluid that’s already in the system.
2. Inspect the brake pads:
If the brake pads are worn down to the metal backing, they need to be replaced. To replace the brake pads, follow the instructions in your bike’s owner’s manual.3. Check the brake caliper alignment:
If the brake caliper is misaligned, it can cause the brake pads to rub against the rotor unevenly. To realign the brake caliper, follow the instructions in your bike’s owner’s manual.
4. Inspect the brake rotor:
If the brake rotor is warped or damaged, it needs to be replaced. To replace the brake rotor, follow the instructions in your bike’s owner’s manual.
5. Inspect the brake cable:
If the brake cable is stretched or frayed, it needs to be replaced. To replace the brake cable, follow the instructions in your bike’s owner’s manual.
6. Inspect the brake lever:
If the brake lever is damaged, it needs to be replaced. To replace the brake lever, follow the instructions in your bike’s owner’s manual.
If you’re not comfortable performing these repairs yourself, take your bike to a qualified bicycle mechanic for service.
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