BELL 4FORTY MIPS MTB helmet, solid white, size M (55–59 cm)

BELL 4FORTY MIPS MTB helmet in solid white, size M (55–59 cm) is a mountain bike helmet engineered for trail and all-mountain riding. It integrates a multi-impact shell construction with MIPS rotational impact protection to help reduce rotational forces in certain crash scenarios. The helmet balances coverage and ventilation, and includes an adjustable retention system for a secure fit during off-road use.

Advantages

The helmet provides rotational impact mitigation through the integrated MIPS system combined with a multi-impact capable shell, delivering added protection compared with a basic single-impact construction. Ventilation channels are designed to promote airflow on longer climbs and technical descents. An adjustable retention system allows quick size fine-tuning for comfort and stability, while the solid white finish offers a neutral, low-visibility aesthetic that is easy to pair with different kit.

Suitable for

• Trail riding and enduro / all-mountain cycling where additional rotational protection is desired
• Day-long rides that require consistent ventilation and comfort
• Riders seeking a mid-size helmet (55–59 cm) with an adjustable fit system
• Mountain bikers who prefer a straightforward, solid-colour helmet design

When it may not be suitable

This helmet is designed primarily for mountain biking and off-road use; riders who need a road-specific aero helmet or a full-face downhill helmet with chin protection may find it inadequate. Additionally, those outside the 55–59 cm head circumference range will require a different size for proper fit and protection.

Key specifications

• Intended use: Mountain bike / trail / all-mountain
• Size range: Medium fit for 55–59 cm head circumference
• Protection features: MIPS rotational protection and multi-impact shell elements
• Ventilation: Multiple airflow channels for passive cooling
• Fit system: Adjustable retention mechanism for secure fit
• Finish: Solid white color

How to use

Place the helmet level on your head so the front edge sits just above the eyebrows. Adjust the retention system and side straps until the helmet feels snug but not tight; the helmet should not move significantly when you shake your head. Fasten the chin strap and adjust it so you can fit one or two fingers between the strap and your chin. Inspect the helmet for damage before each ride and replace it after any significant impact or when signs of wear compromise protection.

What to consider before purchase

• Measure head circumference to confirm the 55–59 cm medium size is appropriate
• Decide whether MIPS rotational protection and multi-impact shell characteristics match your riding style and risk tolerance
• Check compatibility with any goggles, communication systems, or accessories you plan to use
• Consider alternative sizes or models if you require full-face coverage or road-specific features

Usage recommendations

Use the helmet for trail and all-mountain riding where a balance of ventilation, fit adjustability, and rotational protection is required. Replace the helmet after any significant crash, and follow manufacturer care instructions to maintain the integrity of protective liners and the MIPS system.