The use of helmets for cycling can become the subject of heated debate, partly because of the desire of some people to not have a decision legislated upon them, and for some people the overall benefits are not clear. The argument often used is that in countries where cycling is much more accepted and commonplace, most people do not wear helmets and the injury rate seems to be lower than places where helmets are law and less people ride. Part of the reason for this is that the more people cycle, the safer it becomes for the road users (cyclists and motorists alike). Also in countries like Danemark and Holland, cycling is part of the culture. Here in North America, we are slowly getting there, though we still have a long way to go. Google the subject and you will find lots of information.
Here in BC it is the law to wear a helmet, and I think it is a good idea to wear a helmet. Even if it was not legally required, I would be wearing my helmet. I am amazed at the number of people I see biking with a helmet hanging from the handlebars. What is that all about? It wont protect your head, or prevent you from getting a ticket. (A $29 fine by the way) Face it, all it takes is a simple little fall, even at low speed, with your noggin hitting the concrete or a rock....with potentially devastating results. That is why it is so important for young children learning to ride to wear a proper cycling helmet
Having said that, don't expect that a helmet will make you invincible, particularly in a high speed crash with another object. Wear one, but ride like you are not wearing one!
Proper helmet fitting and care is crucial. Did you know that most modern helmets are only good for one impact. That even means dropping it from a few feet off the ground! This is a good reason why you shouldn't buy a used helmet, particularly if it is showing any sign of wear and tear. The foam also breaks down after several years of exposure to the elements. The best thing is to go to your local bike shop to get help in fitting your helmet properly and to see if you need to replace it. (There are good illustrations on the internet as well for helmet fitting)
Look out for, and research some of the new technologies coming out soon for helmet design. One design coming out this year is a helmet with it's own synthetic scalp that helps prevent rotational injuries. This type of injury often results in a much more serious harm than a straight concussion. You want to have a helmet with a smooth surface that will slide instead of getting caught on the ground and thus twisting your neck.
Statistically, those countries with no helmet laws have a higher ridership and thus safer roads, but are you willing to take a personal risk just to prove a point? New helmets are lightweight, relatively inexpensive, and here in BC, it is the law for everyone on a road to wear a helmet, for both children and adults.
Remember the days when hardly anyone wore a seat belt in a car? Now most of us don't even give it a second thought. So put your lid on, get out there, and have fun!