You can trust Cyclingnews
Our experts spend countless hours testing cycling tech and will always share honest, unbiased advice to help you choose. Find out more about how we test.
Image 1 of 8
Giro says its new Synthe is its most aerodynamically efficient road helmet - but it's also very well ventilated at both fast and slow speeds, light, and comfortable(Image credit: James Huang/BikeRadar)
Fast, light, sleek, comfortable, and well ventilated - what's not to like?(Image credit: James Huang/BikeRadar)
The Roc Loc Air retention system and the deep interior channels create lots of room for air to circulate(Image credit: James Huang/BikeRadar)
Helmet ventilation has little to do with the number of vents, but everything to do with how incoming air is allowed to flow(Image credit: James Huang/BikeRadar)
The Roc Loc Air retention system is easy to adjust and comfortable. Just be careful if packing it into luggage for a trip as we haven't always found it to be the most durable(Image credit: James Huang/BikeRadar)
The tapered tail is a big departure from how helmets have traditionally been styled over the past few years(Image credit: James Huang/BikeRadar)
Giro says the 'Aero Mesh' side panels allow air to pass through the helmet without overly impacting on how air flows over the shell. In addition to bringing in air, the larger holes are perfectly placed for stowing eyewear(Image credit: James Huang/BikeRadar)
The sleek and compact shape is one of the keys to the Giro Synthe's aerodynamic performance(Image credit: James Huang/BikeRadar)
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. While we weren't able to verify this in a wind tunnel, Giro boldly claims that the Synthe's sleek shape and unusual 'Aero Mesh' side panels lend it some fantastic advantages in terms of drag. It is said to be faster than even the company's own Air Attack (at least in typical 'head up' riding positions), and supposedly speedier than the decidedly more radical-looking Specialized S-Works Evade.
The trim profile minimizes frontal area
Even if you strip away those aero claims, however, the Synthe is still an outstanding helmet in its own right. 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.
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 (we got mostly positive feedback during testing, but what negative feedback we did get was awfully negative); 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.
Specification Name: Synthe Built by: Giro Price: £200 Helmet Sizes Available: Large 59-63cm, Medium 55-59cm, Small 51-55cm
