Bike Brake Fluid

Brake fluid is essential for transmitting the force from your brake lever to your brake pads and for keeping your brakes working smoothly and reliably.

Two main brake fluid types are used in bicycle disc brakes: DOT fluid and mineral oil. DOT fluid is the standard hydraulic fluid used in car brakes, and it is regulated by the Department of Transport (DOT). Different grades of DOT fluid, such as DOT 3, DOT 4, and DOT 5.1, have different boiling points and viscosity. Mineral oil is a synthetic oil that is not regulated by any authority. It is very similar to the oil you would buy at the pharmacy.

Mineral vs DOT Brake Fluid

Both types of brake fluid have their pros and cons. DOT fluid has a higher boiling point than mineral oil, which means it can withstand higher temperatures without losing performance. However, DOT fluid absorbs water over time, lowering its boiling point and making it more corrosive to metal parts. Mineral oil does not absorb water, so it maintains its properties longer and does not damage metal components. However, mineral oil has a lower boiling point than DOT fluid, so that it may fade faster under extreme heat.

The type of brake fluid you need depends on the brand and model of your brakes. Some manufacturers use DOT fluid exclusively (such as SRAM), while others use mineral oil exclusively (such as Shimano). You should never mix different types of brake fluids or use a different type than what your brakes are designed for. Doing so can cause serious damage to your brakes and compromise your safety.

Maintainence Tips

You should change your brake fluid regularly to keep your brakes working optimally. The changing frequency depends on several factors, such as how often you ride, how hard you brake, what kind of terrain you ride on, and what type of brake fluid you use. Generally, you should change your brake fluid at least once a year or whenever you notice any signs of degradation in your braking performance (such as spongy lever feel or reduced stopping power).

Changing your brake fluid requires some tools and skills that may not be available to every rider. If you are not confident or experienced in doing this task yourself, we recommend taking your bike to a professional mechanic who can do it safely and efficiently.