My rotors on my mountain bike (these are HS1 rotors with elixir 9's) have been given a bit of TLC when I swapped wheels recently. They were removed along with the pads and given a bit of a sand down to remove any glazing on both of them.

No once I had taken them off of the original wheels and cleaned them up with some wet and dry I noticed that the rotors have worn to the point of a significant step on both sides (probably equivalent to ~.75mm or 30 thou in old money in total), how thin should I let the rotors get before I swap them out?

I always use sintered pads which are quite aggressive anyway but refuse to use organics because I go through them in races, not the kind of longevity I am after.

Thanks STW,
Max.