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Bell 4Forty MIPS review

Bell's mid-range 4Forty feels safe and comfortable on the trails

Our rating 
4.0 out of 5 star rating 4.0
GBP £90.00 RRP | USD $110.00 | AUD $180.00
Mountain bike helmet with MIPS

Our review

A safe-feeling, comfortable-to-wear lid that looks good but suffers from some heat build-up
Pros: Very comfortable with a deep-dish fit and MIPS protection at a reasonable price
Cons: Can get hot on slower climbs
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Pitched as Bell’s mid-range lid, does the 4Forty helmet benefit from its years of research and experience?


Bell 4Forty helmet details

The 4Forty is built with an in-mould polycarbonate shell – which covers and protects the EPS foam liner – that extends around the bottom lip of the entire lid.

It also has built-in MIPS protection, which is designed to help reduce the transfer of rotational forces experienced in a crash to the wearer’s brain.

The retention cradle is adjusted with an indexed thumb wheel on the rear of the lid and has four positions of vertical adjustment. It goes around the entire circumference of the helmet, so the fit is adjusted from all sides rather than just the back and sides seen on other systems.

There are 15 vents in total with internal channelling between them. The peak is height-adjustable, moving high enough to store goggles on the front of the lid.

The padding has a Sweat Guide to help keep sweat away from the wearer’s brow as or when it begins to drip down.

The Bell 4Forty wasn’t included in Virginia Tech’s helmet safety impact tests.

Bell 4Forty MIPS
It’s also available in plain black.
BikeRadar / Immediate Media

Bell 4Forty helmet performance

The 4Forty’s got a generous, comfortable and neutral fit that engulfed my head convincingly without any pressure points or hot spots.

It’s easy to tighten and remains comfortable once it’s cranked right the way up, thanks, I think, to the 360-degree retention adjustment system.

I noticed the helmet’s pressure increases evenly around the head as the thumb wheel is tightened. The thumb wheel is easy to operate on the move, too, and micro adjustments of the helmet’s fit can be done at will.

The lid never wobbled or jumped around on tricky, fast or rough descents and I always felt well-protected thanks to its deep coverage.

The pads also felt luxurious and soft against my head even after a long day in the saddle or when they were saturated in either sweat or rain water.

I found the lid worked well with a host of different glasses, their arms not contacting the retention cradle in a way that caused discomfort.

Glasses were also easy to take on and off without needing to fiddle with the arms to get them to sit in the correct position.

Extra-large sized goggles did tend to push the lid rearward on my head, though, or, if the lid was pushed back into place, the goggles down over my nose. However, this wasn’t an issue with small and medium-sized goggles or if the retention cradle was set to its shallowest position.

In the shallow position the lid still felt fairly secure, helped by the goggles further bracing it on my head.

The straps were also comfortable thanks to a large surface area and the splitters can be adjusted with one hand.

Unfortunately, the 15 vents are fairly small and the forward-facing ones don’t reach very far down the lid. This means ventilation is limited and I found the 4Forty to be pretty hot.

Heat build-up was particularly bad when I was travelling slowly and wanted my head to be as cool as possible. The internal air channels don’t appear to aid with cooling in any significant way, a problem no doubt caused by the small vents.

Luckily the pads are good at absorbing plenty of sweat and once they were saturated, the Sweat Guide did a great job of stopping the drops running down my forehead or the insides of my glasses.

This meant putting up much with the 4Forty running hot on the climbs was much easier.

Bell 4Forty helmet bottom line

The 4Forty’s an excellent helmet with top-notch comfort for wearing all-day. It offers plenty of coverage and feels safe and secure. It does run quite hot, so if you’re looking for a trail or XC-biased lid, you might want to consider something else.


If cooling isn’t your top priority, though, the Bell 4Forty is a solid bet.

Product Specifications


Price AUD $180.00GBP £90.00USD $110.00
Weight 360g (M) – as tested
Brand Bell


Features Sizes: S, M, L, XL
Vents: 15
Features: Goggle adjustable visor, Sweat Guide
Colours (include): Black, Sand/Black, Black Camo, Grey/Crimson
Helmet type Mountain bike open face