How To Adjust Caliper Brakes On Bicycle. This is where your Allen key comes in. Follow 3 steps to adjust.

There is a bolt on the center of your bike frame with the cable wrapped around it. The calipers are metal brackets that squeeze the brake pads against the rotor to slow down your bike. Loosen the caliper mounting bolt usually a 5 mm allen.
Adjusting bike brakes disc.
Shimanos spec is 8-10 Nm. Locks the position of the adjusting knob so it doesnt go out of whack. You can often tell this by eye- squeeze the brakes and make note of whether the brake pads meet the rim at the same time. Caliper Brakes Caliper brakes can easily be adjusted using the barrel adjuster near each lever.

