Is the hydraulic disc brake leaking?

One cannot tell if the hydraulic brake really leaks according to its greasy surface. It depends on the actual performance when braking.

Cleaning

1. Remove the disc pads and clean up all the stuff.

2. Blow-dry them with an air gun.

3. Fill a check block into the disc first and press the brake lever to check whether the oil is sufficient. It needs oiling if it feels loose.

4. Remove the disc again and clean it all up after oil filling again in case of misjudgment.

Leaking Test 

1. With a check block filled in the disc, press the brake lever 5-10 times to observe whether there is oil leakage in each part.

2. Remove the block. The disc piston may be leaking if the surface is stained. In this case, we need further confirmation.

3. Gently pinch the lever. It definitely leaks if there are bubbles coming out, which means the entire disc needs to be replaced. (It is much better to find a professional bike shop to do the replacement.)

4. On the contrary, it proves that the disc is in good condition with neither oil stains on the block nor bubbles.

Tips for Hydraulic disc brake maintenance:

1. Clean the dust around brake levers and disc regularly;

2. Check before riding whether there is abnormal sound;

3. When going down a long way, it is better not to brake continuously for a long time;

4. Please use mineral oil.