I have pushed the hydraulic pistons fully out, but after a single firm squeeze of the brake lever, they ride slightly too tightly, such that rear wheel doesn't spin freely. It rubs a little bit. How can I permanently adjust the pistons to a wider default set point whenever the lever isn't being squeezed?
Bike is 4 months old, so brakes, rotors, and fluid should in theory be new enough, and visually look good.
When I finely align the brake, then manually push the pistons out, the wheel spins very freely. It's only after the first firm squeeze that it goes back to lightly rubbing.