Giro Radix trail helmet reviewed

Giro’s new trail helmet introduces new styling and MIPS protection and evolves some favourite features

Giro Radix helmet review
(Image: © Guy Kesteven)

BikePerfect Verdict

Radix mixes excellent safety, security and universal fit with decent venting at all speeds and a reasonable price


  • +

    MIPS protection without compromised cooling

  • +

    Excellent fit and stability

  • +

    Full hardshell


  • -

    Peak is more style than substance

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Radix is the latest in a long line of excellent trail lids from Giro including the original Terramoto and more recent Xen and Hex helmets. Unsurprisingly it takes a lot of cues from them but also adds a new styling and venting approach.  


While recent Giro trail helmets have been about fewer, larger vents the Radix follows other designs like Smith’s Forefront by using more smaller vents. That said there are still two long ‘road style’ centreline vents for speed cooling with another 8 angled apertures set into the ‘ribcage’ top and then a gallery of window vents around the side and rear. Three small front vents and three medium-sized exhaust vents, plus a shallow band of channelling around the inside complete the air-con arrangement.

The in moulded hardshell covers the full helmet, with a slight step down behind the ears for increased occipital protection. This MIPS version also gets an internal cradle floating on elastomers to reduce peak impact load transfer. The Roc Loc 5.5 fit cradle is dial adjusted for circumference with 4 height settings on an internal ladder. Straps are attached inside the helmet with an adjustable Y buckle each side and the POV visor can be angled through 15 degrees.

Giro Radix helmet review

The MIPS cradle is shaped to reduce interference with venting as much as possible (Image credit: Guy Kesteven)


MIPS is generally regarded as a very good thing for reducing brain damage during crashes but the necessary inner cradle often reduces venting performance. Giro has obviously worked hard to minimise the cradle area and then align it with the multiple vents. That translates to a pleasantly breezy feel right through the speed range from centreline airflow when you’re pinning it to useful heat radiation when you’re crawling uphill or stood at the top with your heart hammering. Slim anti-microbial padding keeps sweat retention and eventual stink to a minimum too.

The short peak is mainly a styling exercise as it’s not long enough to offer much weather protection beyond the helmet rim eyeline but it stays in position fine and doesn’t rattle or otherwise irritate. 

Weight and pricing are par for the course for a well-specced, full hardshell MIPS helmet, but if you don’t believe in the Swedish safety system the standard Radix is £89.99 in the same size and colour range.

Fit and comfort have always been a standout Giro advantage worth paying for though and that continues to be true with the Radix. The ultra-stable pressure point free security of the RocLoc 5.5 system combined with seemingly universal shaping certainly made it an instant fit and forget hit with all our northern UK test team.

Giro Radix helmet review

A generous number of vents across the helmet allow plentiful airflow and heat radiation (Image credit: Guy Kesteven)


It’s hard to really stand out in a very crowded trail helmet market but doing it with high-level protection and excellent fit seems a very smart way of doing it. Add decent air con at all speeds, plus a tough build and reduced stench for a long and happy life and the Radix keeps Giro right up in the all-round helmet rankings.

Tech spec: Giro Radix trail helmet  

  • Sizes: S, M, L, XL (black only)
  • Colours: 5
  • Weight: 306g
  • Price: £109,99
Guy Kesteven

Guy has been working on Bike Perfect since we launched in 2019. Hatched in Yorkshire he's been hardened by riding round it in all weathers since he was a kid. He spent a few years working in bike shops and warehouses before starting writing and testing for bike mags in 1996. Since then he’s written several million words about several thousand test bikes and a ridiculous amount of riding gear. To make sure he rarely sleeps and to fund his custom tandem habit, he’s also penned a handful of bike-related books and talks to a GoPro for YouTube, too.

Current rides: Cervelo ZFS-5, Forbidden Druid V2, Specialized Chisel, custom Nicolai enduro tandem, Landescape/Swallow custom gravel tandem

Height: 180cm

Weight: 69kg