Avoid Head Injuries
Many cities have designated areas for cyclists, but not all do. Even with those safety measures accidents can not always be avoided. Rainy weather can cause slips and falls and with so many pedaling away, running into each other in the literal sense of the word, or a vehicle, has occurred on numerous occasions.
On top of the list of injuries are those sustained to the head. Some of them have even been fatal and it is no wonder that wearing Bicycle Helmets has become law in many countries. This protective headgear can and will prevent a lot of unnecessary damage, or worse.
Even if it is on a voluntary basis, many refuse to wear them. Some don't like it for esthetical reasons, while others find it to inconvenient having to haul their Bike Helmets around with them. No matter what justification they come up with, it is better to be safe than sorry.
One may not anticipate or expect it, but keep in mind that accidents do happen!