I've been struggling with this back brake since I got the bike. It was noisy from the beginning, but I thought it would go away. Instead it got worse, and developed into a super-loud harmonic honk each time I hit the back brake. The Trek 8.4 DS comes with Hayes Dyno brakes so I contacted Hayes. Their support has been very responsive. Following their suggestion, I removed the glaze from the pads and tried to bed them in again. Last night I rode around the parking lot making hard stops and thought I was making progress. But, the harmonic vibration started showing up again. This morning, with cold brakes, the sound is coming back strong. I'm getting discouraged. A certain amount of noise is expected, but when people turn their heads to see what the problem is, it's too much.
Has anyone else experienced this? The Hayes tech indicated that a noisy back brake is a known issue, specifically with the 8.4 DS. I would love to find a solution to this problem that doesn't involve buying new brakes.