I have a CUBE Attain road bike with a Shimano Claris setup. I've had the bike for nearly a year and tracked 1300 miles on Strava. I first changed the original brakes in November at about 900 miles ridden. Since then, I have gone through about 5-6 sets of different brakes. Just last week I changed the whole back brake unit cable and gave the rims a thorough clean. It seemed to work, but now today on inspection the brake pads are worn down and I can see the residue building up. My commute is 3 miles twice a day but only 4 times a week. I'm starting to suspect it's the rims, but I'm not sure.
What could be causing my brake pads to erode so quickly?