Which one of these (1/125, 1/15, 1/60, 5 seconds) shutter speeds is best for photographing a sports event such as running or cycling?

1/125. To photograph sports, you need to employ fast shutter speeds. The perfect shutter speed really depends on the type of sport. For instance, if you are photographing a running event it is best to start off with a faster shutter speed. If this is inadequate you may need to increase the shutter speed higher until you find the perfect one. This will allow you to capture actions, such as those during a 100m sprint.

However, if you are interested in photographing racing cars in action, the higher speed means that you will need even faster shutter speeds. This will capture that specific moment in time, when the car was in a standstill.