If you’re new to this, here’s the skinny. Remove the caliper from the bike. You don’t have to disconnect the hydraulic lines, just unbolt the caliper from its mount. If the pads are removable with the caliper in place, and assuming you have enough room to work, you can skip that first step. Remove the old pads. It won’t take much to force most pistons back into their bores. A pair of moderately strong thumbs should do the trick. If your thumbs aren’t up to it or if you’re retracting multiple pistons, which may take a bit of fiddling to prevent back pressure from extending one or more of the opposing pistons, here’s a little trick: Place the old pads back into the caliper. Insert a pry bar or large screwdriver between the pads and wedge them apart. This will force all the pistons back into their bores at the same time. If that seems crude, feel free to use snap-ring pliers or anything else you fancy. The piston should retract smoothly. If it’s stubborn and there’s evidence of a caliper problem, such as dragging brakes or premature pad wear, a piston may be sticking in the bore. If that’s the case, repairs should be made before the new pads are installed. Consult your favorite mechanic or the manual before proceeding. Don’t forget that retracting the pistons will displace some brake fluid. If you’ve been topping off the reservoir along the way, it may overflow, so keep an eye on it in case some needs to be drained out.