Specialized S-Works Prevail II helmet review: Light, airy, and aero

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The original Specialized S-Works Prevail was already tech editor James Huang’s favorite helmet for long days of climbing in hot summer conditions. With the second-generation S-Works Prevail II, Specialized sought to improve the helmet’s aerodynamic efficiency, but without impacting the other areas where it performed so well. So was the company successful in its mission? Seemingly, yes.


Aerodynamic efficiency is, without doubt, the hottest topic when it comes to high-end road helmets. Everyone seemingly wants to go faster or exert less effort — or, at least, so the bike industry would like you to believe. But when it comes to helmets, the traditional metrics of ventilation, weight, and comfort still matter.

The original Specialized S-Works Prevail certainly nailed the traditional aspects of helmet performance, being ultralight, incredibly well ventilated, and comfortable to wear even during long days in the saddle. And as it turns out, it already was pretty aerodynamic as well.

Specialized S-Works Prevail II
The Specialized S-Works Prevail II carries over all that was good about the previous version, while improving (slightly) on its aerodynamic performance.

Alas, some riders didn’t like how the mushroom-like profile sat up high on your head, and when it comes to aerodynamics, less drag is always better. And so this second-generation Prevail II boasts a notably trimmer profile that hugs the head closer than before. The exterior is smoother with fewer ridges and lips to trip the air flowing over the outside, and that squared-off tail is much more tapered and rounded. The prominent tail featured on the original Prevail has been replaced with a much more subtle lip, too.

According to Specialized, those changes result in a six-second improvement relative to the original Prevail over a 40km time trial.

That’s all well and good, but what about those other performance criteria? Thankfully, the Prevail II is still pretty amazing outside of the wind tunnel, too.

Specialized S-Works Prevail II
Overall, the newer Specialized S-Works Prevail II (left) sports a much more rounded shape than the original Prevail (right), as well as a smoother exterior.

But also better, period

While the original Prevail was already remarkably light at just 211g (size small, CE-approved sample), the comparable Prevail II is actually even lighter at a stunningly feathery 196g. Ventilation performance doesn’t seem to have suffered in the least, either. While the vent count may have changed slightly, the combination of huge exterior ports, deep interior channeling, and straight flow-through paths throughout still yield an incredible amount of air passing across your head at both high speeds and low — meaning I stayed cool while cruising along on the flats, and didn’t bake in the sun on long, steep climbs. This was my go-to helmet on ultra-hot days this past summer when I valued airflow above all else.

Specialized S-Works Prevail II
The front-facing Mega Mouthport plays a key role in keeping your forehead cool and dry.

As before, ventilation performance up around the forehead is particularly good, thanks in part to Specialized’s trademark “Mega Mouthport” vent, which feeds air directly to the browpad area. There’s also a generously sized gap in between that pad and your forehead, another typical feature of high-end Specialized helmets, that further helps keep that area dry.

Even the shape of the browpad itself has been tweaked to help keep sweat from dripping into your eyes. Two small tabs at either end of the pad extend downward slightly, helping to redirect perspiration toward the sides of your face instead of straight down the front. It’s similar in concept to what Bell offers in the Zephyr, albeit less effective in that it only works if you keep your head relatively level (and, ironically, it’s similar to what Bell did with the Avalanche mountain-bike helmet in the late 1990s). Still, it’s good to see helmet companies direct more attention to this area, regardless.

Specialized S-Works Prevail II
Small extensions on the browpad are designed to help direct sweat down the sides of your face instead of into your sunglasses. I found them to be only marginally effective, though.

Specialized has carried over its more oval headform, and whether it works for you will obviously depend on your particular head. That said, the interior of the Prevail II is lined with more padding than the original Prevail, and the revised Mindset II retention system has also moved some of the hard, plastic bits away from your occipital ridge. Ella CyclingTips editor Anne-Marije Rook notes that the newly cut-away rear of the Prevail II is more ponytail-friendly than the original Prevail’s straighter cut.

Further helping things out in the comfort department are the thin webbing (which is anchored directly to the lower edges of the helmet liner), handy height and circumference adjustment on the retention system, and fixed strap splitters that create more room around your ears — although there’s no allowance if the stock setting doesn’t work for you.

Specialized S-Works Prevail II
A new V-shaped cutout on the back of the Specialized S-Works Prevail makes it more ponytail-friendly than the original version.

There’s no easy way for me to comment on whether any improvements have been made in terms of safety, since companies are legally restricted from stating anything aside from whether or not they pass government-mandated test standards. That said, it’s worth noting that, like on the original Prevail, Specialized again uses a dual-density EPS liner for the Prevail II that theoretically manages impact energy better than single-density foam, and hidden away inside is an aramid fiber skeleton to help keep the helmet from breaking apart during a crash.

Absent is the increasingly popular MIPS low-friction liner, or any similar feature that would supposedly reduce rotational forces on a rider’s brain during a crash.

Specialized S-Works Prevail II
The combination of huge exterior ports, deep internal channeling, and straight flow-through paths make for outstanding ventilation at both high and low speeds.

Otherwise, downsides are fairly trivial.

Although the Prevail II seems to be an improvement over the earlier version on all performance fronts, there’s quite a bit more exposed foam than before. The lower edges are thankfully still covered by a polycarbonate shell, but there’s enough bare foam up top that ham-fisted riders should still take extra precautions when storing or transporting this thing. There’s also no designated spot to stash sunglasses — although in fairness, I’ve often found that those sorts of things rarely work as well as claimed, anyway.

All in all, the Specialized S-Works Prevail II may be pricey, but if you care more about ventilation, weight, and comfort than aerodynamic performance, this helmet is tough to beat.

Price: US$225 / AU$350 / £175 / €240

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