MET Trenta 3K helmet review: Aero and airy

by James Huang

Aero helmets are widely regarded as being one of the most cost-efficient ways to squeeze out some extra speed. I’ve used a lot of them over the years, and almost without exception, they’re invariably an exercise in compromise. The MET Trenta 3K, on the other hand, seems to sacrifice virtually nothing in its quest for free speed: it’s lightweight, well ventilated, looks pretty good, and is even comfortable to wear for long days in the saddle. It’s also quite inexpens … ok, well, maybe there is one compromise. It is still just a bicycle helmet, after all, not a unicorn.

A two-pronged approach

As is becoming increasingly common these days, MET’s road helmet lineup is headlined by a pair of distinctly different models, not just one lone flagship: the Trenta 3K that’s being reviewed here, and the Manta. Of the two, the Manta is the more dedicated aero lid, and it’s along the lines of what you’d expect from the genre.

The shell is mostly closed-off with minimal forward venting, the profile is closely cropped all around, and in general, it’s crafted specifically with sprinting in mind. In other words, it supposedly helps you go faster when you’re at top speed with your head down. Although it’s surprisingly lightweight at just 200g (claimed, size small or medium), ventilation performance is clearly secondary.

The Trenta 3K, on the other hand, is more of an aero-minded all-rounder. It’s slightly more elongated than the Manta, with more of a subtle teardrop profile when viewed from the top — a more appropriate shape for “heads up” riding. The frontal profile is still very admirably trim, but there’s clearly a lot more ventilation on tap here. Whereas the Manta has a sparse array of rather tiny slits to help draw in cooling air at speed, the Trenta 3K’s vents are much bigger and more generously distributed throughout the front and top.

The MET Trenta 3K is lightweight, well ventilated, and, if you take the company at its word, it’s supposedly pretty aerodynamic, too.

Shared between both the Manta and the Trenta 3K is a distinctive port up top that is meant to actively pull air in for additional cooling power. Combined with the generously sized exhaust ports, the claim is that air is actually sucked out the back of the Trenta 3K while you’re riding, instead of just being pushed in through the front.

According to MET, the aero penalty for that improved ventilation performance is fairly modest. Whereas the Manta is claimed to save a rider 10 watts when moving at 50km/h (a realistic figure for sprinting), the Trenta is supposedly only about three watts behind. It’s also similarly light with an actual weight of 217g for a small CE-certified sample. Keep in mind, however, that helmets for American and Australian markets will be likely be about 20-30g heavier.

For a helmet to be aero, that once meant a mostly closed-off shell and mediocre-at-best ventilation performance. But those days thankfully seem to be over.

As suggested by the name, carbon fiber is said to play a key role in the Trenta 3K’s performance. A genuine carbon fiber outer sub-shell help keeps the helmet together during an impact, and allows for a lower weight and a smaller outer profile. The latter not only helps with the overall aesthetics, but also aerodynamic performance: a smaller helmet punches a smaller hole in the air, after all. And yes, that exposed carbon weave does look pretty cool, too.

But just as you’d expect, that carbon fiber adds to the Trenta 3K’s cost, too. Retail price is a rather premium US$300 / AU$450 / £265 / €330. For those on more modest budgets, MET also offers the standard Trenta at about two-thirds the cost. It trades carbon fiber for a more conventional polycarbonate shell on the outside, all for just a 10g claimed weight gain.

Winner, winner, chicken dinner

All of that marketing hype about the Trenta 3K’s ventilation performance obviously goes up in smoke if it doesn’t hold up in the real world, but I’m happy to report that it really is quite exceptional in that regard. While that fancy “NACA” vent up top seems more show than go — it’s basically sealed off once the helmet is on your head — the combination of generously sized vents and deep internal channeling with minimal obstructions is still a time-tested formula that’s yet again proven here; there is absolutely a lot of air moving through the Trenta 3K to help keep you cool.

That 3K carbon fiber is the real deal. It helps keep the weight down, but also helps hold the helmet together during a crash. It also makes the Trenta 3K quite expensive.

Several aero helmets (such as the Giro Vanquish MIPS and Specialized S-Works Evade II) are surprisingly good at maintaining excellent airflow at speed, but their more closed-off shells quickly morph into sweatboxes when you’re slogging up a hard and steep climb.

Not so with the Trenta 3K.

Thanks to all that open area around the shell, plus the fact that very little of the Trenta 3K’s interior is actually in contact with your head, heat can readily dissipate into the atmosphere, even at speeds barely above walking pace. And despite not having any specific mechanisms to manage sweat, the Trenta 3K still does a very good job of keeping perspiration from dripping down into your sunglasses.

Credit likely goes to the noticeable air gap between the forward part of the EPS foam liner and the browpad, plus the fact that the backside of the browpad isn’t squashed against a totally solid strip of plastic. As a result, incoming air has a reasonable chance of getting that sweat to evaporate before it becomes a problem.

The profile is admirably low.

And if and when it’s just too hot and humid for the Trenta 3K to keep things under control, MET thankfully hasn’t forgotten about eyewear storage. Sunglass temples line up perfectly with the outermost vents up front on the Trenta 3K, and there are also a pair of small gripper pads to help hold them in place (although their effectiveness seems dubious at best).

The Trenta 3K scores a win on the comfort front as well, at least assuming you’ve got a reasonably ovoid head.

That low weight is basically unnoticeable even after three or four hours in the saddle, there’s ample padding, and the retention system is not only refreshingly minimal, but also highly customizable. In addition to the usual circumference adjustment — operated here with a convenient one-handed dial — there’s also four height positions for the cradle along with two width positions for the rear occipital pads. The straps are pleasantly lightweight with secure locking sliders, too.

The retention system is easy to adjust, and quite comfortable. Eyewear interference can be an issue with glasses that have particularly long temples, though.

As for how aero the Trenta 3K really is, that I unfortunately can’t say as I didn’t do any objective testing that I would consider to be rigorously scientific. That said, it’s worth noting that the Trenta 3K is a noticeably quiet helmet to wear, a trait that I’ve often found to go along with some of the most aggressive aero claims in the industry. Even when descending long and fast mountain passes, wind noise is sufficiently subdued that you can still hear cars coming up from behind. If only for safety (and sanity) reasons, that’s a big plus in my book.

Minor complaints

All of this sounds like a home run so far, right? Well, almost.

I’d like to see MET add a secondary shell that wraps around the entire lower edge of the Trenta 3K to guard from everyday wear and tear. After several months of regular use, there are a few spots on my sample that are starting to look a little beat-up. And while I found the Trenta 3K to be very comfortable overall, I’d still prefer that the straps were anchored in the lower edge of the helmet, where they’re less likely to get tangled up, instead of further up in the interior.

One odd thing about the Trenta 3K’s aesthetics is how the front of the helmet is quite long. If you ride with your head tilted down, the front of the helmet can actually obscure your upward vision a bit.

There’s also the subjective question of aesthetics. In general, I think the Trenta 3K is a pretty good-looking and clean design, free from a bunch of silly adornments. But while the subtly tapered front and trim tail are probably good in the wind tunnel, it still makes for a lot of foam sticking out ahead of your forehead. Whether that offends your sense of style is obviously up to you to decide, but anyone who tends to ride with their head tilted down and with the helmet positioned low above their eyebrows (as I do) may find that the front of the Trenta 3K slightly cuts off your field of view.

And if I really want to nitpick, the range of available colors is rather limited. There’s the white with black carbon fiber as shown here, an all-black option, a black with blue-tinted carbon fiber, and then a mostly red UAE-Team Emirates team replica. Want something brighter or a bit more off the beaten path? Sorry, you’re out of luck.

What about MIPS?

One key performance aspect I haven’t discussed yet is safety, which, needless to say, is of primary importance when it comes to a bicycle helmet.

Virginia Tech’s independent lab has rapidly emerged as the premier third-party test facility for bicycle helmet safety performance, and given the Trenta 3K’s niche market — not to mention MET’s relative obscurity when compared to bigger players such as Giro, Bell, Specialized, Bontrager, Lazer, and others — it’s no big surprise to see that this helmet still doesn’t appear on the organization’s latest rankings. So aside from confirming that the Trenta 3K satisfies local government test requirements, I unfortunately don’t have much to add here.

Notice something missing here? Sorry, folks, there’s no MIPS liner available.

One thing that is worth mentioning, however, is the lack of any sort of rotational safety element in the Trenta 3K. The top 23 helmets on Virginia Tech’s rankings all feature MIPS or something similar, and while that’s not outright confirmation of the feature’s effectiveness in preventing traumatic brain injuries, it sure seems hard to discount it entirely. Currently, none of MET’s road helmets include MIPS or anything equivalent, so safety-focused riders will likely want to keep that in mind when shopping. But that said, that position may be changing moving forward.

“MET holds all of their helmets to 20% beyond the required threshold for testing (CE, CPSC, ASTM), making them significantly stronger and safer than competitors,” said Lori Barrett of Rotor USA, who distributes MET in the United States.”They have chosen to invest in this additional testing, rather than MIPS. However, MET is moving toward more MIPS helmets in the range, since the cycling customer finds it an easy-to-understand safety indicator.”

Let’s just call it a triple

Ignoring the questions about safety, the Trenta 3K is otherwise quite compelling, as it ticks all the critical boxes when it comes to performance on the road, while seemingly giving up very little in exchange. That said, it still wouldn’t be my pick for anyone keeping a close eye on their bank account; that honor would fall to the standard Trenta, which offers the same aerodynamic performance, is only about a dozen good snot rockets heavier than the Trenta 3K, presumably offers the same level of protection, and yet costs about one-third less. It’s offered in a bunch more colors, too.

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