I've replaced rotors and pads on auto disc brakes myself for decades. Mechanically the differences between bicycle and auto hydraulic discs have to be minimal save aspects of size and scale. On the autos, often a 'special tool' was necessary as the caliper pistons required rotating while moving them back into the caliper bores during re-padding operation. I've not yet read that this is an aspect confronting bicycle techs when dealing with hydraulics so that's one minor difference.

Is it simply a matter of opening the bleed port before repositioning a caliper's pistons when performing what would have avoided the OP's mishap?

Are the various designs of bicycle hydraulic discs so different that basic maintenance is unique to each?

Put in simple terms, the procedure for replacing pads ought to be what needs to be understood by an owner confronted by what the OP's asking about, right?


True that while also being a fine way to lighten your wallet if you go in head first. You'll learn much by DIY, ask me how I know.