What would a hydraulic brake system be without hoses? These hoses carry the lifeblood of the system, namely the brake fluid, from the reservoir, to the master pump, and to calipers. No fluid, no brakes!
Assuming that your bike is fitted with rubber brake hoses, they need to be replaced every four years, regardless if they still look and smell like they left the factory 2 hours ago.
Brake hoses take lots of beating as they try to resist expanding when the brake is applied. Over time, the pressure gets the better of them and they DO expand, resulting in that vague feel at the lever.
Also, they may crack on the inside. These chips may go on to block the passages in the system, resulting in either no brakes or locked brakes.
Old rubber hoses may also become porous, meaning they are permeable to air and moisture. Both degrade the brake fluid’s performance, as in reducing the boiling point. The boiling moisture will contribute to air pockets in the system, causing sponginess.
So, okay, your rubber hoses are up for replacement. You may want to consider replacing them with steel braided ones. Why are they better?
The downside if of course the cost. A good, reputable set of hoses can cost around RM 700, but the benefits are priceless.
One note, though: Don’t skimp. There are really cheap steel braided brake in online shopping platforms that we are not sure of their quality. It doesn’t mean they’re all bad, but just be careful because if it’s too cheap, chances are it’s too good to be true.