Originally Posted by carcassonne

Folks,

I'm relatively new to disc brakes in general. And in montain biking which means that I apply brakes more often than experienced riders do, although I'm becoming more confident in my skills now. So, for the regular cleaning/maintenance of the bike I tried to get the rear brake mechanism as tight as possible (eg. as close as possible wihtout rubbing) when I noticed that when doing that the disc rotor would rub only during a small part of the circumference as I tighten up the barrel at the brake lever. The brakes are Avid BB5.

Taking a closer look in the gap between the rotor and the pads I saw that indeed the rotor was out of true as it seems. Torx screws are holding the rotor to the hub and the screws seems well in place. So I located the place of the rotor where it went against one of the pads and applied a bit of pression in the other way using my fingers. To my surprise this produced an effect.

So this is new to me, that disc rotors can warp and, can respond to finger pressure. I thought these things would be made of some kind of very strong metal and would always stay straight in normal use.

My question then: is disc rotor truing a common thing to do ? If so, is there a way to easily mesure the trueness (eg. like truing wheels in a truing stand) and are there tools to do this ? And lastly, if there are tools to do that, is it worth while to invest in them of woudl fingers or a pair of long nose pliers or some such be OK ? - Thanks.

Cheers,
Al