Description of The Problem
When the rider releases the brake lever after slowing down, the brake arms remain partially closed. The brake lever usually doesn’t return to its original position either.
Possible Sources Of The Problem
Rim brakes. This problem is more common when the bike relies on rim brakes (e.g., V-brakes, calipers, cantilevers…etc.) Rim brakes slow down the bike by directly grabbing the rim and creating friction between the rim and the brake shoes.
1. Contaminated Brake Cable
Rim brakes and mechanical disc brakes are controlled via a steel cable. When the brake lever is closed, the cable pulls the caliper arms which then rotate around a pivot point and bring the brake shoes to the rim or disc rotor.
The cable sits inside an enclosure known as housing. If the cable and its housing are contaminated, the cable could fail to return to its starting position after braking is initiated.
There are two solutions.
A) Replace the cable and housing
B) Remove the cable from the housing. Clean it with a rag and re-lubricate it with a small amount of oil.
If those actions do not resolve the issue, the problem lies elsewhere.
2. Malfunctioning Brake Lever
To isolate the brake lever, unhook the brake cable from it. Then, squeeze and open the brake lever. The movement should be effortless. If it isn’t, the brake lever is damaged or there’s an external object preventing its proper function. Observe the lever for deformities. If the lever is damaged, replace it.
Note: The brake lever isn’t spring-loaded. It returns to its initial position due to the spring found on the brake. Do not expect the brake lever to re-assume its starting position when the cable is disconnected from it.
3. Brake Shoes With a Lip (Uneven wear)
Ideally, the entire surface of the brake shoe will be in contact with the rim. If the brake shoes’ height is not adjusted properly, however, a part of the brake shoes will not touch the rim.
The section of the brake shoe that doesn’t experience friction will remain the same (unworn) while the rest of the pad will keep getting smaller.
The unaffected area will develop a lip. If the lip is near the tire/upper part of the rim, it may be catching the rim or the tire’s sidewall. When the rider initiates braking, the lip would stop the brake arms from returning to their initial position.
The solution is to replace the pads and readjust their height so that the entire surface of the brake shoe sits on the rim.
4. Malfunctioning Brake Spring
If the caliper spring is not in order, there’s nothing to push the brake arms back to their original position.
The possible issues are:
- The spring is out of position
It’s possible for one end of the spring to bounce out of alignment. When that happens, the spring is practically non-existent. The solution is to press the “freed end” back to its original location.
In the image above, you see a set of caliper brakes common for retro road bikes.
Notice that the two outer ends of the spring are sitting behind a pin found on each brake arm.
If the spring is pushed away from the brake arm, the spring will pop out and render the brake non-functional.
V-brakes use separate springs for each arm rather than one unit for both sides.
Meanwhile, mechanical disc brakes have a coil spring that sits in an enclosure.
The location of the spring in this case makes it close to impossible for the spring to be disengaged.
However, it’s possible for the area to get contaminated with debris preventing the rotation of the lever arm connecting the spring to the brake cable. In rare cases, the spring could also break.
If the spring is just contaminated, the issue can be resolved by removing the retention bolt and cleaning the area. If the spring is broken, it will be necessary to find one compatible with the brakes in question and replace it. Thankfully, the springs of quality mechanical disc brakes rarely experience this issue.
- Rusted/Corroded Springs
Since the springs are made of steel, they are subject to some degree of corrosion. If a spring rusts heavily (unlikely but technically possible), it could become hard to move and in some rare cases, it can snap.
Hydraulic Disc Brakes
Unlike rim and mechanical disc brakes, hydraulic disc brakes do not use a brake cable. The braking is triggered by hydraulic fluid in the hoses.
When the rider squeezes the brake lever, the fluid is pushed toward the brake calipers. Then, the fluid reaches two separate chambers containing a piston right next to each brake pad. The fluid then presses the piston towards the brake pad. The brake pad has no choice but to go toward the disc rotor and grab it.
Once the lever is released, a rubber seal around the piston pushes the piston back a fraction of a millimeter, and the pressure on the brake pads is released. They return to their original position.
If the brake is not opening back after use, the problem is more than likely air inside the braking fluid. In order for the fluid to be maximally effective, it has to be free of air bubbles and contaminations.
For that reason, hydraulic brakes are bled. The bleeding process is different for each brand. The purpose of the procedure is to replace the old fluid with a new one and eliminate air bubbles.
If that’s the problem, the brakes will feel squishy and ineffective regardless of how hard you grab the lever.
In rare cases, the problem could come from the pistons inside the caliper. If they’re worn or contaminated, they could fail to go back. This will keep the brake pads partially closed even when the brakes are not in use.