Wanted to share some of what I've learned on riding my St2. Crushed Granite seems to be popular these days where I live. Since hearing some of the grinding in either the brake caliper or cluster , I avoid the stuff like the plague. Big Bens tread seems to like to pick the bits of Granite up and then drop them into bikes workings. Walking the bike seems to be where I've heard the sound most frequent. Not a very good one .