The choices for a modern bicycle helmet can be overwhelming with numerous different styles, price ranges, and purposes to choose from. It can also be extremely confusing why one helmet costs $30 and another $220 yet they both passed the same CPSC crash testing. But first off let me cover the major features and what extra cost gets you in return and then I will break up helmets into a couple of broad categories of cycling. There are sport or casual helmets, mountain biking helmets, road biking helmets, time trial helmets, and full face helmets.
Helmets are made up of a foam or padding interior that is protected by a hard exterior shell. The foam will deform upon impact and protect your head. (Side note – once the foam in a bike helmet has deformed it can no longer be used and MUST be replaced.) One of the first upgrades with price is to have the shell molded to the foam instead of glued or taped which allows for weight savings and larger vents for cooling. To keep the helmet on your head there is the strap that comes under your chin and a ratcheting retention system that wraps around the back of your head. All quality helmets will have a means to tighten and loosen the retention system although more expensive helmets allow for more exacting fit while weighing less. Also, look for the chin strap to lay flat against your skin and not twist or it will probably aggravate you as you ride.
Casual helmets are what can be commonly found at big box retailers and also make up the lowest range of helmets at bike shops. Casual helmets serve only one purpose which is to protect your head in the event of a crash however they will lack or have cheaper versions of the features found in dedicated purpose helmets as well as be pretty heavy.
Mountain Biking Helmets
Mountain helmets are similar to casual helmets although more refined. They will usually have larger vents to help with cooling the head and be significantly lighter while still included an improved retention system to dial in a perfect fit. Mountain biking helmets commonly come with a visor on the front.
Road Biking Helmets
With road helmets the priority is dropping weight because it is such a weight fanatic discipline of cycling. Road helmets will have the largest vents to most effectively cool the head off at the higher speeds and exertion levels of road cycling.
Time Trial Helmets
Time Trial or Triathlon helmets are pretty much a subset of road helmets except moving the priority from weight and cooling to aerodynamics. They use a teardrop shape to allow wind to flow over the rider with the least drag as possible. This is useful in triathlons and time trials because drafting is illegal and all riders are out in the wind alone unlike in road racing.
Full Face Helmets
Full face helmets are just like motocross helmets and are really only used in downhill mountain biking racing because of their weight. The full face provides significantly more protection to the head and face but at significant weight gains. However, as downhill mountain bikers don’t go uphill weight is not important and it is also the most dangerous discipline of cycling.
The big advantages of more expensive helmets is a more exact fit, weight savings, and increased venting without sacrificing crash worthiness. All helmets will help to decrease the risk of injuries from a crash equally however the nicer the helmet the more comfortable it is to wear and therefore the more likely you as a rider will wear it. Only a helmet that is worn can help protect you. When purchasing any helmet make sure to check the inside for a CPSC sticker that certifies the helmet’s crash worthiness and must be present to be legally sold in the US. $50-100 will put you into the entry levels of quality helmets and is where I recommend most people to start. You don’t necessarily need a featherweight but you do need something comfortable enough to want to wear.
The YouTube video below is great as a basic overview of bicycle helmets and helps with the fitting process.