How to Check the Alignment of your Wheels
For safety and performance, it's a good idea to double-check the alignment of your wheels in your bicycle frame.
Open your quick-release lever, leaving it in position, and then apply pressure straight down on the saddle or stem. While still applying pressure, reconfigure your quick-release skewer to its original position.
Now that you're sure your wheel is properly centered and aligned in the frame, you can check the alignment of your brake pads. Simple squeeze the brake level while observing the actuation of the brake caliper. Both pads should contact the braking surface of the rim squarely and in unison.
If one pad touches before the other, it's a good idea to check the torque of the brake caliper fixing nut. If the nut is loose, you will likely see some free movement of the caliper. This nut is typically adjusted with a 5-millimeter hex wrench. However, many of the new calipers use a torx nut. Either should be tightened to 10 newton meters. This is slightly more torque than used to shut off a leaky water faucet.
Once the nut is properly torqued, you can make adjustments by holding either brake arm and manipulating the caliper. Finally, confirm the proper adjustment of the caliper by once again squeezing the lever.