Giro Synthe helmet review

Does this helmet offer the best of all worlds?

Our rating 
4.5 out of 5 star rating 4.5
GBP £200.00 RRP | AUD $399.00 | USD $250.00

Our review

Aero, airy, light, and comfy – if you're after a new road lid, we'd urge you to give this a once-over
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Aero road helmets have historically been an exercise in compromise: you could have a speedy shape, good ventilation, low weight, or sleek aesthetics but not all four. Giro finally breaks that paradigm with the new Synthe.


The Synthe admittedly doesn’t look like many other aero helmets, aside from its notably trim profile – not only does it fit close to the top and sides of your head, it also sports a distinctly clipped tail that’s fast becoming the norm with modern road lids.

The sleek and compact shape is one of the keys to the giro synthe’s aerodynamic performance:

The trim profile minimizes frontal area

Even without the aero claims, the Synthe is still an outstanding helmet. The surprisingly open architecture, for example, provides lots of forward-facing ports to bring air along with – more importantly – deep internal channels and sizeable rear ports that give that air a smooth path through the shell and out the other side. Out on the road, we found the Synthe to be exceptionally well ventilated not just at cruising speed (where even helmets with minimal ports can often move sufficient air to feel cool) but also when slogging up steep inclines in stifling summer heat (where even many non-aero helmets often fall flat).

Moreover, the Synthe is also comfortable for all-day rides despite its relatively sparse padding. Credit here goes to the spindly Roc Loc Air retention system, which is not only adjustable in circumference and height, but also serves to partially suspend the helmet’s foam liner off of your head – thus decreasing the contact area and reducing the chance of hot spots or pressure points. The lightweight nylon webbing feels softer against your face, too, and doesn’t absorb as much sweat as the thicker stuff that’s more commonly used, either.

Helmet ventilation has little to do with the number of vents but everything to do with how incoming air is allowed to flow

Deep internal channels, big vents, and clean, unobstructed paths for air to flow make the Synthe very well ventilated at both high and low speeds

Finally, the Synthe is light – and not just light for the category but seriously light, period. Our CPSC-approved small-sized sample weighed just 209g on the BikeRadar scales, putting the Synthe roughly in line with some of the lightest options out there.


For sure, the Synthe’s aesthetics won’t suit everyone, nor will the moderately oval shape work for everyone’s head. Otherwise, however, we can’t think of any compelling reasons not to get one of these if you’re in the market for a new road helmet.

Product Specifications


Name Synthe helmet
Brand Giro

Helmet Sizes Available Large 59-63cm Medium 55-59cm Small 51-55cm