Disc brakes offer many advantages.

Because the disc is mounted at the center of the axle, brake performance is less likely to degrade even if it gets wet in the rain.

Also, since braking is achieved by clamping the disc, the rim does not need to be as strong, allowing for a lighter overall weight.

Since they don't scratch the rim, with proper maintenance, you can keep your bike looking good for a long time.

In the professional world, the UCI lifted the ban on disc brakes in 2018, leading to an increase in teams using disc brakes.

In Japan, disc brakes were also permitted in 2019 by the JBCF (Japan Bicycling Federation) and JICF (Japan Intercollegiate Cycling Federation).

The share of disc brakes in races worldwide is expected to continue to grow in the future.

When to replace disc brake pads

Disc brake pads are consumables.

Naturally, they need to be replaced once they wear down to a certain extent.

However, compared to rim brakes, disc brake pads are thinner, making it difficult to determine when they should be replaced.

If you keep using them without paying attention, the pad material can completely wear away, causing the backing plate to press against the disc, which will damage the disc.

Looking at Shimano's instruction manuals, new pads have a thickness of about 2.0 mm, and replacement is necessary when about 0.5 mm remains.

Since 0.5 mm is half of 1 mm, it's hard to tell by sight.

Using calipers to measure is reliable, but it means disassembling the pads every time.

Disc Brake Issue: Squealing

One of the weaknesses of disc brakes is "squealing."

That's the high-pitched "screech" sound that occurs when you apply the brakes.

While various methods for stopping this noise have been suggested, the best one is said to be "replacing the pads themselves."

However, squealing is caused by oil or dirt adhering to the pads.

Considering Shimano pads, they can cost around 2,000 to 5,000 yen, depending on the model.

If they start squealing right after purchase and you have to replace them, I think that would be a great waste.

While replacing pads is not a bad way to stop the noise, it's not the only method.

Incorrect methods for stopping squealing

First, I'd like to introduce some methods found online that are ineffective.

Unless there's a special trick involved, these methods generally didn't improve the situation when tried normally.

(Incorrect) Heating with fire

(Incorrect) Boiling in hot water

(Incorrect) Cleaning with parts degreaser

(Incorrect) Cleaning with parts cleaner

Heating with fire can warp the rubber.

However, if oil is present, it cannot be degreased.

Therefore, the noise cannot be stopped.

Boiling in hot water may degrease, but if the surface is too flat, the noise will still occur.

Degreaser and parts cleaner are likely used for degreasing, but these alone are not completely effective in stopping the noise.

3 steps to correctly stop squealing

The cause of brake pad squealing, as mentioned above, is oil or dirt adhering to the pads, and noise can also occur when the pad surface is too flat.

Therefore, you can stop the squealing with the following three steps:

1. Disassemble the pads and wash them with neutral detergent
2. Roughen the pads with sandpaper
3. Wash the disc rotor with neutral detergent

There's a high probability that reassembly will stop the noise.

In other words, by roughening the pad surface and degreasing both the pads and the disc, there's a high chance of improvement.

Wash the pads with neutral detergent.

This removes any oil from the pads.

A simple wash is sufficient, but either leave them out overnight to dry or use a hairdryer to heat and dry them.

Next, roughen the pad surface with sandpaper.

When doing this, use quite coarse sandpaper, around 60 to 100 grit.

Sandpaper is usually used wet, but in this case, use it dry.

Press the pad surface against the sandpaper and move it in an arc.

At this time, try to move it as horizontally as possible.

If you move it too quickly, only the edges of the pad will be abraded, which will reduce its effectiveness.

The resulting debris can cause new problems, so after thoroughly brushing it off, rinse it with water again.

After cleaning with a brush or similar tool, dry it again.

Finally, remove any oil from the disc itself.

Wash it with neutral detergent and wipe it thoroughly.

Disassembling the tire to wash it is a lot of trouble, so place a rag or cloth behind the disc and apply neutral detergent.

You can degrease it by scrubbing with a soft-bristled brush.

Rinsing is also important, so wipe thoroughly with water or rinse to ensure no detergent residue remains.

Summary

Disc brakes offer significant advantages, making them beneficial as a braking system and increasingly popular.

However, if they start to make noise, it can be a bit troublesome, so it's good to know how to stop the squealing.

Removing oil from the disc and pads and roughening the pad surface can eliminate squealing.

External Writer - Koichi Okuno