You know that it is smart to wear a helmet when you ride your bike, but did you know that not all bike helmets are the same? It is critical that you understand the differences between the different styles and how to pick the right one for you.
For instance, many mountain bike helmets have visors on the top. This helps to block the sun and gives you a little more protection. Since there is no vehicle traffic on the trails, you can keep your head down and not worry about the way that the visor cuts off some of your forward vision. Additionally, mountain bikes have straight handlebars and you ride them sitting up a bit higher than road bikes, so the visor isn't in the way.
On a road bike, though, that same visor can actually put you in danger. When you duck over and hold the low handles on your bike, it swings down into your field of vision. You can't see traffic and potential hazards in your path. You keep having to bring your head up to check.
Instead, you're much better off to get a road bike helmet without the visor, and then you can just wear a pair of sunglasses to protect your eyes. These won't obstruct your vision on the city streets in California.
These are just two examples, but they really do illustrate how even little factors can contribute to a crash. And, while helmets are far safer, they by no means prevent all bike injuries. If you do get hurt, make sure you fully understand your legal rights.