Could this convertible helmet from Sweet Protection be the ultimate enduro lid?

We take a look at Sweet Protection's new convertible Arbitrator MIPS full-face helmet

Sweet Protection Arbitrator

The Arbitrator is a convertible helmet from Norwegian brand Sweet Protection, and has been in the making for a good couple of years with extensive feedback from downhill and enduro legend Tracy Moseley.


It’s fully DH-certified (in its full-face configuration) and can quickly and easily be converted into an open face trail helmet by removing the lower section of the helmet and chin bar.

It’ll set you back a cool £269 and weighs 1,010g in its full-face guise and a not-so-light open face 550g lid with the chin bar removed (size medium).

Sweet Protection Arbitrator MIPS safety

Sweet Protection Arbitrator
Comfy padding sits on top of the MIPS liner which is designed to better protect your head against angular/rotational impacts. Sweet Protection claims its high-grade, low-density EPS liner is able to deal with impacts more effectively when compared to the higher-density equivalents found in most bicycle helmets.
Andy Lloyd / Immediate Media

In a bid to limit compromise in both its open and full-face configurations, Sweet Protection has done things a little differently to the majority of brands out there.

For starters, it’s more than just a chin bar that detaches when you release the single safety lever at the rear.

Whip it open (and initially at least, you’ll need strong thumbs to actually get this released because it’s reassuringly stiff to operate) and disconnect the alignment lugs that sit in the opening of the helmet, and it’s the lower half of the full-face as well as the chin bar that detaches from the open face lid.

The safety lever which locks the lower half of the helmet into place is actually designed to snap off in a crash and prevent any kind of accidental release, which is good to know.

Sweet Protection Arbitrator
A single locking lever allows you to safely fix the chin bar onto the open face helmet.
Andy Lloyd / Immediate Media

Sweet’s big selling point here is just how safe it’s designed the Arbitrator to be and says: “there’s no compromise given to safety by making it convertible”.  As a full-face helmet, it’s DH certified, meeting the stringent ASTM F1952 Downhill Mountain Biking safety standard.

Inside you’ll find a MIPS (Multi-directional Impact Protection System) liner, which is designed to better deal with angular impacts to your head.

Sweet Protection Arbitrator
Removing the Arbitrator’s chin bar is easy enough but does leave you with a sizeable chunk of carbon to carry on your pack or hanging from your handlebars.
Andy Lloyd / Immediate Media

Underneath the yellow layer of MIPS and the padding sits the EPS (Expanded Polystyrene) shell. According to Sweet Protection, it’s produced one of the highest levels of EPS shells on the mountain bike market, which boasts a lower density (most helmets use an EPS shell around 100g/litre while the Arbitrator’s is closer to 80g/litre) and should in theory do a better job of absorbing impacts.

The outer shell of the helmet uses a four-piece construction with variable Polycarbonate thicknesses used in key areas of the helmet, all of which is built around an internal nylon resin frame. To help keep strength where it’s needed without bumping the weight up too much, the chin bar is made from carbon fibre.

Sweet Protection Arbitrator MIPS fit

While most convertible helmets use one set of straps and a retention cradle to perfect fit, Sweet has decided to do things a little differently in a bid to ensure no matter how the helmet is configured, it should fit well and feel properly stable.

Although the Arbitrator’s retention cradle is nothing out of the ordinary and offers the usual indexed adjuster dial to help tailor fit around the head, as well as some vertical adjustment, Sweet has included two sets of helmet straps; one for each helmet.

Sweet Protection Arbitrator
Sweet Protection uses two sets of chin straps to limit compromise in fit. The straps for the open face lid tuck up inside the helmet when you’re using it as a full-face.
Andy Lloyd / Immediate Media

The open face helmet straps are pretty standard for the most part and can be neatly stowed up and out of the way when you’ve got the chin bar fitted (there are small flaps that they can be tucked into).

The quick-release ratchet style buckle used on the chin bar is a neat piece of design, though, and not only allows for some quick and easy adjustment once it’s closed, but it can be released one handed with next to no hassle. The straps also get some welcome padding for improved comfort.

By designing the Arbitrator in this way, Sweet has also been able to use what it calls, “proper cheek pads” to improve fit further.

Sweet Protection Arbitrator MIPS venting

With no mesh covering any of the chin bar vents, we’re hoping the Arbitrator should be fine to wear on long, physically taxing enduro stages, and should suck in air easily enough.

Sweet has included three hefty brow ports as well as numerous other vents and exhaust ports throughout the Arbitrator’s shell, though it’s by no means as vent-littered as many of the other convertible lids we’ve seen.

Far from it in fact, and is one of the contributing factors to its overall weight (1,010g when compared to Bell’s Super DH helmet which weighs 880g).

Sweet Protection Arbitrator
Decent size exhaust ports help to keep air flowing across the top of the head. A retention cradle allows you to tailor fit easily using just one hand.
Andy Lloyd / Immediate Media

Still, we don’t think that’s necessarily a bad thing and don’t mind carrying the extra weight if we know our heads are well-protected.

There’s also a number of sizeable internal channels to help with airflow across the top of the head. The peak is adjustable though not to the same extent as those found on convertible lids from MET, Giro and Bell.

Sweet Protection Arbitrator MIPS sizes and colours

Finally, the Arbitrator is available in three sizes – S/M, M/L and L/XL – covering head sizes from 53 to 61cm. And, if you’re not a fan of the stealth black helmet seen here, it also comes in blue and matte green.

For those with a keen eye, it’s worth mentioning that while you’re unlikely to see any pro Enduro World Series races rocking either a lightweight full-face or convertible helmet, instead favouring all out full-face lids designed for the ultimate protection, Sweet claims the Pole team choose to wear the Arbitrator over its standard full-face offering.


We’ll have a full review of the Arbitrator alongside its contemporaries very soon, so be sure to keep any eye out for those.