I'm trying to replace my brake pads but when I try to push one piston in, the other one will come out and when I push it back in the previous one will do the same... how do I fix this so that both pistons remain retracted?
2 Answers
You need to push both pistons at the same time. There are tools for doing this, but many of us use a large flat bladed screwdriver.
You need a steady firm pressure for a few seconds to force the fuild in the lever back into the reservoir. Have a look at this Park Tool video - about 4:10
It turns out there's a lot of air in the brake system, it stopped when I open the lever cap and pull the lever for a few times.
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The hint with the lever cap worked for me. I had the very same issue with two pistons caliper Shimano BR-MT200, One pushed, the other comes out. The trick for me was to open the lever cap and then push one of the pistons and the other - they are pushed inside the caliper successfully in that way I lost around 10-15 drops of break fluid (it was too much). Few months ago, I went to a bike service to purge the air from the read brake and filled it to the top. This caused the issue, i had too much break fluid.– mihkovMay 15, 2021 at 14:54