Shoulder checking is important because bicycles and riders are narrow and can easily be hidden in your blind spot. Make sure you shoulder check before you (a) open your door to get out of your vehicle, (b) pull away from the curb, (c) move to the left to merge onto a highway, or (d) move to the right to pull off to the side of the road. However, if you want to check if you’re being tailgated, use your mirrors.