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One of the pistons on my front brake isn't retracting when I close the lever.
These are SRAM Rival calipers on my gravel bike.
Have tried cleaning and lubricating, have worked the pistons in and out several times, etc.
No noticeable improvement.
Anyone got any suggestions?
Drain and re-bleed totally following the SRAM instructions on YouTube, there could be some air in there
Is it the piston not retracting or the SRAM weirdness where they get less lever throw when the pads wear?
Realign the caliper. The pistons aren't supposed to literally retract through the seals. The seals grip the piston and flex when you apply the brakes. When you release them, the seal returns to its original shape and the piston retracts just enough to stop the pads rubbing. When the pads wear too much, the piston resets itself in the seal.
To realign the caliper, gently push the pads apart with a clean flat screwdriver to push the pistons back into the caliper. Refit the wheel and put a feeler gauge or shim cut from a drink can between each pad and the rotor. Loosen off the caliper mounting bolts just enough to let the caliper align itself. Pump the lever until the brakes are fully applied and then carefully tighten the mounting bolts. Remove the shims. This should leave the caliper aligned and the pistons reset with just enough of a gap to avoid pad rub.
Bleeding the system won't make any difference. The problem isn't caused by air in the system.
Yes the realign helped. It's about 80-90% better now.
Glad it helped.