Bike helmets come in a variety of shapes and styles. You’ll find specialized cycling helmets for road cycling (lightweight, well-ventilated), mountain biking (more coverage, visor), triathlon (aerodynamic), and freestyle/BMX (maximum coverage, minimal ventilation). All these lids share four — sometimes five — common traits: a hardshell outer cover; a thick inner shell; an inner liner or comfort pads against your skin; a chin strap; and, in some cases, an adjustable retention system. All these components work together to protect your skull in a crash yet stay comfortable enough that you’ll want to wear the helmet every time you ride. So let’s dive in and find out what each bike helmet part does.
Bike Helmet Shell
The shell is just what it sounds like; it’s the thin hard plastic or polycarbonate cover that protects the softer foam underneath from nicks, scratches, dings, and other insults. To minimize wind resistance, it's more aerodynamic than the foam underneath, plus its hardness helps the helmet keep its shape to a degree.
Bike Helmet Foam Liner
The thick expanded polystyrene (EPS) foam liner is the actual material that protects your head in a crash, making it the most important element in any bike helmet. Upon impact, it disburses the force throughout the rest of the foam liner instead of letting your head absorb the shock directly. In many helmets, the EPS foam is integrated with the exterior hard shell for durability. Rudy Project goes one further and uses a polycarbonate exoskeleton in some of its helmets to boost the EPS foam’s durability and protective qualities while allowing larger ventilation slots to keep you cool.
Advanced helmets use MIPS Brain Protection construction that inserts another slick and thin layer of material between the shell and the EPS liner. This separation allows the helmet to rotate upon an angled or side impact, further dissipating the force smashing your head. At Rudy Project, rotational impact performance is a big deal. So much so that we adopted the WG11 testing protocol to make sure every helmet we design adheres to the standards advocated by CEN, the European Committee for Standardization.
Bike Helmet Comfort Pads or Inner Lining
Comfort pads line the inside of the helmet. They feature a small amount of padding and a soft fabric facing that rests against your hair and skin. They attach via Velcro, which allows you to adjust them for a customized and comfortable fit. This versatility also lets you remove them for washing, which you’ll want to do, as the most prominent comfort pad will sit on your forehead and double as a sweat sponge to keep perspiration from dripping into your eyes. Even better, a smart design, such as Rudy Project’s Integrated Airframe pad, maximizes airflow to reduce sweat in the first place.
Bike Helmet Chin Strap
As you’d expect, the chin strap keeps the helmet on your head in a crash. Without one, or with one that’s not properly fitted to your head, your helmet is essentially useless, no matter how well-designed the EPS foam shell is. An ideal fit is tight enough that you can feel the strap under your chin if you open your mouth wide but not loose enough that it can slide off your chin with your mouth closed.
Bike Helmet Retention System
While a chin strap keeps your helmet secure vertically, a bicycling helmet’s retention system secures the helmet horizontally (side-to-side, front-to-back) by cinching a strap system tight across the back of your head. The strap connects to the sides and front of the helmet and further allows you to “dial” in a customized fit if the helmet is slightly larger than your head. The RSR 10 Retention System used by Rudy Project does one better: It also adjusts vertically so riders with smaller or bigger heads can further perfect the fit. This snug fit helps ensure that your helmet stays on your head in a fall or accident.