Alpinestars Motocross Helmets

Engineered for motocross, enduro, and off-road riding, the Alpinestars SM3 Radium Helmet combines advanced safety technology, rider comfort, and practical features for high-performance protection in demanding conditions.

Key Features:

• Advanced Thermo-Injected Shell: Special polymer blend with variable thickness for optimal impact protection and reduced weight (1430g ECE / 1460g DOT).
• Superior Ventilation: 10 intake and 7 exhaust ports maximise airflow and heat dissipation.
• Rotational Force Protection: Patented low-friction EPS coating reduces oblique impact forces, mimicking natural cerebrospinal fluid protection.
• Patented Visor Release: Releases at a pre-set force to reduce neck strain during impacts.
• EPS Multi-Density Liner: 5 inner parts with 4 densities for precise energy management.
• Hydration Ready: Integrated tube channels in cheek pads.
• Eco-Friendly Comfort Liner: Made from recycled materials for a reduced carbon footprint.
• Optimised Chin Protection: Reinforced chin bar meets Alpinestars’ higher in-house impact standards.
• Emergency Release System: Removable cheek pads for safe helmet removal.
• Secure Fit: 25mm soft textile chin strap with stainless steel D-rings.

Fully certified to ECE 22.06 and DOT standards, the SM3 delivers premium safety, comfort, and performance for serious riders.

Sizing

To determine which helmet size fits you best, measure the widest circumference of your head using a flexible measuring tape or piece of string; approximately 2cm above your eyebrows and ears as illustrated below. If your head measurement falls between two sizes, it is generally recommended to select the smaller of the two.

For maximum safety and comfort, take note of the following points when fitting the helmet (and securely fastening the chin strap):

• Helmet may take some effort to slide over your head, but should not be overly difficult
• Should fit snuggly around the crown of your head without creating uncomfortable pressure points
• The top padding presses on the top of your head
• The cheek pads press against your cheeks, so that your teeth touch the inside of your cheeks when opening / closing your mouth
• There should be no space to slide two fingers between the helmet and your temple
• Hold the helmet on either side and without moving your head, try to move the helmet up and down, and side to side. It should not be easy to move and you should feel the skin of your head and face being pulled
• Your eyes should be located in the center of the helmet's viewpoint