I took the bike in for its 30k service a couple of weeks ago and my mechanic told me I needed new rear brake pads immediately. Being the noob I am I asked him to show me because I had no idea what I was looking at. Which brings me to my point. If you haven't checked your brakes and/or don't know how - get someone to show you (or google it). Anyway, as he didn't have the brakes in stock I had to order them and decided I would give it a go at installing them. It mostly went well - the hardest part was getting the piston to push back far enough so both pads would actually fit. Now I may still be learning about maintenance, but I'm pretty sure this part of the pad is not supposed to be getting it on with the disc... And yes, this photo is from a few days after I changed them - it took that long to get the dirt and grease off my hands.