Bicycle Mechanics - Disc brake vibrating

I am using 2001 Avid mechanical disc brake, it's new.

When I want to stop on the road, I start to squeeze the brake lightly so that I can stop smoothly over a long distance, but the rear disc brake produced a vibration. At first it was small, than became pretty big, and all happen( vibration from small to big) within 5 to 7 seconds. This started only today, what can be the problem?

I would have to say your problem is that under heat your disc is distorting. I would think that if you have a dial indicator that if you checked it cold it would be in spec. However, after it heats up from hard stopping it distorts.
Is it still under warranty? If not maybe it can be machined.
Good Luck and Happy Riding!

I had this problem with my hayes. It was missing some of the nuts holding it to the hub as well as 2 of the nuts were loose. The bike mech had forgotten locktight. :)

I would also check the bolts holding the rotors on. Everyone of mine have come loose when new. After I tightened them once, they have never come loose again. Since yours is new I would definately check them.

But if I brake hard over a short period of time, say 3 sec, nothing wrong will happen.

could it be the pad material? what kind of cable housing are you using btw?

Originally posted by Mashimaro
could it be the pad material? what kind of cable housing are you using btw?

I am not expert in bike mechanics, so can you explain the cable housing part so that I can check it out? THanx!