April 28, 2022, 10:44 a.m. -  Andrew Major

I'm not exactly sure what you're asking for my thoughts on? If you are 100% certain your brake was last bled with the pistons fully recessed, and it never had the fluid topped up or a lever bleed after that point, then there would be space in the system to fully push in the pistons without damaging the bladder. If the system was bled without the pistons fully recessed or if it received a lever top-up at some point as the pads wore down (which is quite common), then where would that fluid go when you push the pistons back in? The weak point in the system is the rubber bladder. I'm not saying that the bladder _will_ fail if you reset your pistons without opening the lever bleed screw. I'm saying the best practice is to remove the lever bleed screw so that you know there's somewhere for the excess fluid to go if there is excess fluid. Put another way, if you push your pistons back in without removing the bleed screw and your bladder fails, you can't say you weren't informed of the best practice.