Explained: Bicycle Helmet Terminologies

Founder, Mr. Mamil

Struggling to understand the terms used when describing a bicycle helmet?

These terms, sorted alphabetically will help anyone new to cycling understand the essential components and features of bike helmets and their importance for rider safety and comfort.

Adjustable fit system

A mechanism, such as a dial, ratchet, or Velcro strap, that allows the rider to adjust the helmet’s fit for optimal comfort and safety.

Aero helmet

A specialized helmet designed for optimal aerodynamics, with reduced ventilation and a teardrop shape, commonly used by time trialists and triathletes.


The fastening mechanism on the chinstrap, usually a simple snap-together or magnetic closure that can be easily opened and closed.


Helmet safety standards and certifications, such as those from the Consumer Product Safety Commission (CPSC) or European Committee for Standardization (EN), ensure that a helmet meets specific safety requirements.


A strap that goes under the rider’s chin and connects the two sides of the retention system helping to keep the helmet in place during a crash.

Convertible helmet

A versatile helmet that can be transformed between a half-shell and full-face configuration, providing adaptable protection for various riding conditions.

Crash replacement policy

A program offered by some helmet manufacturers provides a discounted or free replacement helmet if the original is damaged in a crash within a specified time period.

Extended coverage

Helmets that offer additional protection around the back and sides of the head, often used for mountain biking and other off-road disciplines.

Full-face helmet

A helmet that covers the entire head and face, with a built-in chin guard and a visor, typically used for downhill mountain biking and BMX racing.

Goggle compatibility

A helmet feature that allows riders to comfortably wear goggles, typically a specific channel or clip system designed to hold the goggle strap in place.

Half-shell helmet

A traditional bike helmet that covers the top and sides of the head, leaving the face exposed, suitable for road cycling, commuting, and casual rides.

Hair port

A feature found in some helmets that accommodates riders with long hair, typically a gap or channel at the back of the helmet for a ponytail or braid.

Helmet sizing

The process of measuring the circumference of the rider’s head to determine the correct helmet size, and ensuring a secure and comfortable fit.

Helmet storage

The options for storing a helmet when not in use, such as built-in clips on a backpack or a dedicated helmet case.

In-mold construction

A manufacturing technique where the helmet’s shell and liner are fused, creating a lighter, more durable helmet with better ventilation.


The inner layer of a bike helmet, typically made of expanded polystyrene (EPS) foam, absorbs and distributes impact forces during a crash.

MIPS (Multi-directional Impact Protection System)

A technology designed to reduce rotational forces during an angled impact by allowing the helmet to rotate slightly around the head, reducing the risk of brain injuries.


Cushioned foam or gel inserts inside the helmet provide additional comfort and help wick away sweat.

Reflective elements

High-visibility materials or decals on the helmet’s surface that reflect light, enhancing rider visibility in low-light conditions.

Removable chin bar

A detachable piece found on some convertible helmets allows the rider to switch between full-face and half-shell configurations.

Retention system

The adjustable straps and mechanisms, such as a dial or ratchet system, secure the helmet to the rider’s head and ensure a snug, secure fit.


The outermost layer of a bike helmet, usually made of hard plastic or composite materials, helps protect the head from impact and abrasions.

Skater-style helmet

A round, smooth helmet with minimal vents, popular among urban riders and skateboarders for its casual look and added coverage.


Openings or vents in the helmet’s shell and liner allow airflow to help keep the rider cool and comfortable during a ride.


A removable or adjustable sunshade that is attached to the front of the helmet. It helps to shield the rider’s eyes from sunlight, rain, and debris.


The overall mass of a helmet. Lighter helmets often provide more comfort during long rides but potentially sacrifice some protection.

Alex Lee at Mr.Mamil

Alex Lee is the founder and editor-at-large of Mr. Mamil. Coming from a professional engineering background, he breaks down technical cycling nuances into an easy-to-understand and digestible format here.

He has been riding road bikes actively for the past 12 years and started racing competitively in the senior category during the summer recently.