Dad I were riding a week or so ago, and I had just come down a nice hill where I had been going over 50 kilometres and hour… Towards the end the brakes on the rear wheel started to make a grinding noise as I slowed down. I’m a bit of a bike newbie, so it seemed to me that there were a couple of options: my brake pads were worn out; the brakes had over heated; or there was grit stuck under a pad.
We stopped and had a look, and the pads seemed to have heaps of rubber left on them, so we went for the grit theory. This was reinforced by the ride home, where the grinding stopped after a little while.
Time passes and I have the same experience last night. Except this time the grinding happens all the way home, so I decided to take the brakes apart when I got home.
It turns out that the brake pads were worn out, and that I had been damaging the rear rim. I don’t think the damage is too bad – -I’ve probably reduced the life of the rim a little, but it’s still usable. The problem was that the break pad has these metal spikes through it to hold it together, and the amount of usable pad is much smaller than it looks from the outside.
I suspect that the grinding went away the first time because the metal spikes in the pad changed shape as it heated up going down the hill, and then changed back as I rode on.
So, new bike brake pads today, and you live and you learn.