First of all, pay attention to your brake feel in daily use, especially after the oil change, if the brake is significantly softer and the stroke becomes longer, it may be that the air in the caliper piston has not been removed. If this is the case, If it is relatively mild, it will generally return to normal after a period of use. If this is the case for a long time, you must consider re-exhausting. If your residence has a vacuum lubricator with hydraulic brakes, it is recommended to replace it for better exhaust. Empty the air in the caliper.
The other thing is to check for excessive wear of the film. Under normal circumstances, as the film becomes thinner with the use of the caliper, the piston of the caliper will protrude more, and the real-time maintenance will ensure a reasonable gap between the film and the disc. This is also a major part of the open oil circuit. Advantage. But when you change the oil, the piston on the caliper will be completely pushed into the caliper due to the block, so if you continue to use the old pad and install it directly on the bike, the brake stroke may be too long, Although you can squeeze the brake a little bit by letting in to make the pad gap smaller and improve the brake lever stroke, the best way is to replace a new pair of pads.
Generally speaking, it must be replaced when the wear of any one side reaches 2/3. The wear of the film is not completely horizontal. In many cases, the wear is inclined, so the wear 2/3 should be the thinnest. The place prevails. At this time, replacement is very necessary. Continued use may damage your caliper.
If your brakes have been used normally, but suddenly start to soften within a few days, the stroke becomes longer, and the brake dead spots are blurred or even disappear, then check whether there is an oil leak. Generally speaking, oil leakage will appear in the brake lever piston part, and some will appear around the caliper piston. If it appears in the piston part of the brake lever, basically just replace the new piston seal to solve the problem.
The oil leakage at the caliper is first eliminated to eliminate the problem of excessive exposure of the piston caused by the excessive wear of the film, and then the Y-shaped sealing ring around the piston should be replaced, or the entire caliper can be replaced directly.
Other problems such as weak brakes, obvious dead spots, but unable to stop. If the brakes have problems such as howling, you can basically replace the pads directly. These conditions are usually caused by oil stains on the discs during wiping, transportation, or even rain. The best solution is to replace the new disc and thoroughly clean the disc.