Disc brakes work by creating friction between the bike brake pads and the bike brake rotor to slow down the bike. Brake pads are made of a combination of several materials and wear down the brake rotor during use. Therefore, the bike brake rotor (also known as the brake disc) and the bike brake pads are both consumable items that require regular inspection and replacement. But when to replace disc brake rotors?

Professional suggestion on when to replace disc brake rotors

Shimano’s suggestion on when to replace disc brake rotors

Shimano recommends that riders regularly measure the thickness of the brake disc. When the brake disc’s thickness falls below 1.5mm, you must stop using it.

SRAM’s suggestion on when to replace disc brake rotors

SRAM recommends replacing your brake disc when it has worn down by more than 0.3mm. In fact, this recommendation is quite similar to Shimano’s. In many cases, brake disc manufacturers will mark the replacement recommendations, such as the minimum operating thickness, on the brake disc surface.

A simpler method

However, this method can be challenging to implement in daily life since few riders have a caliper at home. Fortunately, there is an easy solution. The answer is a US penny coin. You only need a penny coin to easily determine if your brake disc thickness is below 1.5mm. The thickness of a penny coin is exactly 1.5mm, and it’s readily available. If you find that your brake disc is thinner than the penny coin, replace your brake disc immediately, as this is a dangerous sign.

Thickness Is Not the Only Criterion

When it comes to determining whether a disc brake rotor needs replacement, thickness alone is not conclusive. While the thickness of a disc brake rotor is a crucial metric, it’s essential to consider other variables. The rotor’s appearance offers vital clues. Cracks, excessive scoring, or uneven wear on the surface are telltale signs that it’s time for a replacement. Performance degradation is another key factor. If the brakes vibrate during operation, or there’s a reduction in stopping power, this could indicate that the rotor is compromised. Additionally, rotor deformation, like warping, can negatively impact braking performance and safety. Therefore, a comprehensive evaluation, taking into account thickness, appearance, performance, and deformation, is necessary to make an informed decision on disc brake rotor replacement.

Appearance

Inspect the surface of the brake disc for deep grooves or cracks. These issues on the surface will significantly affect braking performance, and you should absolutely replace it. If the brake disc surface shows discoloration or scorch marks, it might indicate overheating, which also warrants replacement.

Performance

If you notice a significant decrease in braking power, hear unusual noises (such as high-pitched squealing) or feel vibrations while braking, the brake disc might be severely worn and needs to be replaced.

Deformation

Rotate the brake disc and observe if there is any noticeable lateral wobble. If the disc is uneven or deformed, braking performance will be compromised, and it should be replaced.

Please implement regular inspections

Regularly inspecting and maintaining your bike’s braking system is crucial for ensuring it remains in good working condition, which is essential for riding safety. If you are unsure about the condition of your brake disc, it is advisable to have a professional technician inspect and assess it.

By the way, SUMLON has been manufacturing bicycle parts for over 15 years. Contact us if you are looking for a bike parts factory or a one-stop wholesaler. Peace