Bicycle Mechanics - Disc brakes: Rotor wear

Hi all,

I'm curious about the effect of wear on disc brake rotors.

-Has anyone ground a rotor down to the limit?
-Are there problems developing progressively or does failure strike without a warning?
-How many sets of pads (on average) can a rotor go through before it is used up?

There's always is a wear tolerance in the service instructions for cars and motorcycles. I don't know if this information can be obtained for bicycle brakes.

I apologize in advance if this subject has been discussed before but I haven't seen it come up in my searches. In fact most threads are about wear caused to wheels by rim brakes.

You worry too much. You'll almost surely bend the rotor badly enough that it has to be replaced long before you'll ever wear it thin. If you don't you're not mountain biking hard enough.

I have a customer that runs through pads about every four months. His last bike had 14,000 miles on it before it broke(The frame that is), the new frame still has the same rotors. The only rotor I have replaced is the one he ran the pads until he wore a hole into the backing plate(He used to take it to a shop that "checked" the brake pads by grabbing the lever

Thanks for your opinions.

I think it must be hard to specify a generic wear tolerance for bicycle brake rotors since they come in several thicknesses. Apparently high-end brake rotors are thinner than "basic" & mechanical brakes.