BELL 4FORTY AIR MIPS mountain bike helmet — BELL — size S (52–56 cm) solid matte black

BELL 4FORTY AIR MIPS is a size S (52–56 cm) mountain bike helmet in solid matte black designed for trail and cross-country riding. The helmet combines an airflow-focused shell design with integrated MIPS technology to reduce rotational forces during certain impacts. Lightweight construction and adjustable fit elements aim to balance comfort and protection for everyday MTB use.

Advantages

The 4FORTY AIR MIPS provides ventilation through a network of intake and exhaust vents that promote airflow across the head. MIPS technology is built into the liner to help manage rotational energy in oblique impacts. The helmet’s adjustable retention system and padded interior allow a customizable, secure fit within the S size range. The matte black finish offers a low-reflective, understated appearance suitable for a variety of riding conditions.

Suitable for

• Trail riding and enduro-style rides where ventilation and impact management are important
• Cross-country (XC) riding that requires a balance of light weight and protection
• Everyday mountain biking and off-road training sessions
• Riders seeking a compact, low-profile helmet with rotational impact mitigation

When it may not be suitable

This helmet is sized for head circumferences between 52 and 56 cm; riders outside this range should select an appropriate size. For disciplines that demand extended full-face coverage (for example downhill racing with high-speed crashes), a full-face helmet would provide more facial and jaw protection than this open-face MTB helmet.

Key specifications

• Size range: S — 52–56 cm head circumference
• Construction: lightweight in-mold shell with internal EPS liner
• Rotational protection: integrated MIPS system
• Ventilation: multi-vent airflow design optimized for trail use
• Fit system: adjustable retention mechanism and padded comfort liner
• Finish: solid matte black

How to use

Measure head circumference at the widest part above the eyebrows to confirm the S size (52–56 cm). Place the helmet level on the head, adjust the retention dial or system so the helmet sits snugly without uncomfortable pressure, and fasten the chin strap with the buckle adjusted for a secure fit. Ensure the helmet sits low on the forehead and does not rock when you shake your head. Replace the helmet after any significant impact or if the fit components become damaged.

What to consider before purchase

• Confirm head measurement falls within the 52–56 cm size range
• Decide if an open-face trail helmet with MIPS meets your protection needs versus a full-face model
• Check compatibility with goggles or eyewear you plan to use
• Consider ventilation needs based on typical riding climate and intensity

Usage recommendations

Use the BELL 4FORTY AIR MIPS for trail and cross-country sessions where ventilation and rotational impact mitigation are priorities. Regularly inspect the helmet for visible damage and follow manufacturer guidelines for replacement after any significant impact to maintain effective protection.