Bought a new Trek Top Fuel 9.8 on Wed. Went out for the 1st ride on Thursday night and when your not pedaling it has a very loud and annoying squaling in the back brake. We loosened it up, recentered it and it worked fine for about 5 miles the started back in even louder. Has the XT's on it. Any suggestions....1st time with hydraulics, didnt know if it takes time for them to break in.