Each disk brake will be assembled and adjusted before delivery; however, please allow a few rides for the brakes to "break-in" before re-adjusting.
There are two pistons that squeezes the brake pads and the disk brakes. The inside piston can be adjusted in or out using a #5 mm hex wrench. If you turn "in" the brake pads will move closer to the disk, if you move out the brake pads will move further from the disk brakes.
The outside piston can be adjusted by tightening the brake cables. There is one adjustment in the brake lever, and another in the brake calliper. You can also use a 5 mm hex wrench to tighten the cable. Tightening the cable will move the piston in -closer to the disk brakes and loosing the cable will move the piston out- further from the disk.
"Tektro Aries" are very easy to maintain and adjust. If you have any questions please do not hesitate in contacting me.