All About Brake Fluid!

Brake fluid makes a huge impact on your brakes performance. The quality of your fluid makes a huge difference in how long your brakes will function properly, as well as how aggressively you can use them. Regular old brake fluid from the auto parts store can do the trick for most any motorcycle, but a higher quality racing brake fluid will make a noticeable difference: Aggressive riders and racers will notice they can rider harder with less brake fade, and the average street rider will notice their brakes will work better for longer periods between fluid flushes. It's easy to exceed the performance of cheap fluid, so paying $15-20 for a bottle of high quality fluid makes for a much safer and better brake system. 

Breakdown and Moisture Contamination

Brake fluid is hydroscopic so it absorbs water/moisture from the atmosphere once removed from it's original sealed container. Over time the water content will rise and the fluid becomes less effective. This happens to fluid that is in your motorcycle's brake system, as well as the leftover fluid in the bottle. It's also something that happens once it's removed from the original sealed container and continues over time.

Your leftover bottle of fluid will start to absorb more fluid as time goes by, thus reducing the effective boiling point when you need the next time. Most manufacturers specify a 1 year shelf life of containers that have been opened and partially used. If you live in a humid climate, you might want to discount that shelf life even further. Always store in the original container with the cap screwed on tightly and always dispose of old fluid responsibly.

The fluid in your brake system will do the same thing, but it can become more obvious when the brakes are used in extreme conditions. Street bikes should be flushed every 1-2 years under average riding conditions but race bikes should be bled 1-2 times per season. This can vary slightly with some aggressive racers requiring fresh fluid more often due to higher demands of tracks with lots of heavy braking.

Boiling Point

Knowing the boiling point of fluid will help you choose a quality brake fluid. The higher quality race fluids tend to have 500-600 degree boiling points, with some even higher than that! That boiling point starts to lower over time due to the fluid absorbing moisture, and this is the big reason you need to periodically flush your brake fluid.

The boiling point is specified as "dry" or "wet". Dry refers to brand new fluid from a freshly opened container, while wet refers to fluid that has absorbed 3.7% water. Safety standards require the fluid to have a stated minimum boiling point for both dry and wet. This will give you an idea of the boiling point of your fluid when it's brand new as well as after it's been used for some time. 

DOT Ratings

Most motorcycle brake systems are designed to use DOT 4 or DOT 5.1 fluid. Pay close attention to your brake components so that you use the correct fluid type. Some aftermarket brake components come with special seals that require DOT 4 only, because other silicone fluid can cause damage to those special seals.

Brake Fluid For Supermoto

Fluid makes a big difference for any bike, but especially converted supermoto bikes that use the stock caliper and master cylinder. Asphalt riding naturally requires more front brake use than offroad riding, so your newly re-purposed offroad bike is going to see a lot more front brake use on the road. It's highly recommended to use a good quality racing brake fluid that will last longer and put up with the high heat demands of asphalt riding.