BRAKE FLUID LIFE: MR. KNOW-IT-ALL

BLEED IT OUT
Dear Mr. Know-It-All,

Hello, sir. I have a Yamaha YZ250 that I ride in the woods. I love this bike and can find few flaws in its character, as it does everything I want a bike to do on the trail.  Lately, though, my rear brake feels weird. The pedal gets spongy and the braking power seems off. I checked the pads and they look fine, so my question is about brake fluid. How often should this be changed? Because, honestly, I’ve never done it.

Tom Riddel
Via [email protected] 

Dear, Tom, please remember that our machines live and degenerate based on the amount of focused maintenance that they receive. Your rear disc brake gets repeatedly abused during an enduro or long bout of woods riding. Heat and moisture are brake fluid’s wort enemies. DOT 3 and 4 are hydroscopic, glycol-based fluids, which means they can and will absorb water over time. The more moisture that is suspended in brake fluid, the more susceptible it is to heat fade. Eventually, the fluid breaks down and needs an IV of fresh juice. I personally cycle out my rear brake fluid every four rides. This keeps the fluid fresh; it will deal with the abuse and heat deterioration, and your pedal feel and stopping ability will remain constant.