The rear brakes on my GT have two ways of letting you know when it is time for replacement, IN THEORY!

The first, is an electronic sensor that when the pad friction material is worn to its limit is worn through and breaks a circuit which tells the onboard computer and turns on a warning light and related symbol on the dash board.

IN THEORY

The second theoretical way to check for wear limits is holes in the pads that align with holes in the caliper. This SHOULD wear though before all the friction material is worn off the pad so you can visually check if the pads are servicable.

Another theory disproved!

I felt that the pads were worn out, but it is hard to see the pads while the caliper is assembled on the bike, so I pulled it off and gave a quick look.

In order to make for much less stress on the brake line, caliper, AND yourself, BEFORE loosening the caliper bolts, pull the safety pin out of the brake pad retaining pin as seen here.

Then drive the retaining pin out of the caliper with a punch or something long and thin. (I use a 2.5 mm t-handled allen wrench.) Now you can pull the caliper off the bike and replace the pads without having to rotate the claiper and twist the brake lines AND trying to support the other side of the caliper while trying to drive out the pin!

Now you can remove the caliper. Remove these two bolts and then gently twist the assembly side to side to side to spread the pads enough to allow the caliper to drop easily.

Looking inside from top of caliper with brake pads still installed.

NO MEAT there!!!

Now before I remove the old pads, I use them to protect the pistons while I push them back into the caliper with a wedge shaped device. A large flat blade screwdriver inserted and turned works well, as do big needle nose pliers.

After removing caliper but not cutting wire ties yet.

note clip for rear speed sensor and brake pad sensor on swingarm.

Rear brake pad wear sensor connector.
It is on the bottom of the swingarm and even with the rear wheel rim (which is seen on right side of picture)

That is one worn out brake pad.

I guess I got full use out of that one!

The interesting part is that neither of the two "designed" indicators worked at all.

The apparently worthless wear indicators for the rear brake pad. These were not worn through at all, but the pad was shot and had just began to chew on the rotor!

New vs. Old pads. This sensor didn't do its job at all, but at least this side had a tiny bit of friction material left on it and wasn't contacting the brake rotor metal to metal.