Remove spikes that are already in the shoes using the spike key. Place the key over the top of the spike, then turn to the left until the spike is completely free from the shoe.
Pinch a new spike between your thumb and index finger. Place the spike in one of the holes in the sole of the shoe with the point of the spike facing up. Twist the spike to the right to start screwing it into the sole of the shoe. Tighten the spike all the way down with the spike key.
Place a spike in each hole. Make sure each spike is tightened down all the way to prevent losing spikes.