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Carnac Kronus Time Trial Helmet



Aero, comfy and cheap, one of the best time trial helmet deals going

At every product is thoroughly tested for as long as it takes to get a proper insight into how well it works. Our reviewers are experienced cyclists that we trust to be objective. While we strive to ensure that opinions expressed are backed up by facts, reviews are by their nature an informed opinion, not a definitive verdict. We don't intentionally try to break anything (except locks) but we do try to look for weak points in any design. The overall score is not just an average of the other scores: it reflects both a product's function and value – with value determined by how a product compares with items of similar spec, quality, and price.

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With the head being the first part of the body to hit the wind, it makes sense to make yours as aero as possible. The Planet X Carnac Time Trial Helmet takes a familiar shape, with a short tail and adds it to a well-fitting, if slightly large helmet. At this price, there's nothing to complain about.

Firstly, I'll state that I'm awful at time trials. I can't concentrate for more than five minutes, my legs refuse to give more than 240 watts and I find my head looking down more than it should. The shape of the Carnac Kronus then, is very helpful. The chopped off tail and smooth lines back there mean that I'm not making a giant wind catcher very time my form fails.

Planet X Carnac Kronus Time Trial Helmet - front.jpg

That stubby shape should be familiar. The Kask Bambino Pro springs to mind and there are many other brands that have used this shortened tail design. One of the ways that a time trial helmet used to fit was at the shoulder blades. With the shortened tail, this is not so important anymore. This opens up the fit options to a wider range of riders and positions. This shape should also be better than its tear-drop shaped rivals when the wind isn't directly head-on.

Planet X Carnac Kronus Time Trial Helmet - visor going on 1.jpg

Keeping the helmet in place is an occipital cradle (the bit that grabs the back of your head) with a claimed 70mm of width adjustment range and 12mm of height adjustment. While it doesn't have as wide of a range of adjustment vertically as a road helmet, I found it to be a secure and comfortable fit. That said, my head sits on the border between sizes. I had the larger size, but this was quite large on my head so I'd want to go for the smaller lid for a closer fit.

Buy Carnac Kronus time trial helmet

The straps are fully adjustable and lock into place with good clips. Once I got them tightened down, they stayed put, preventing any extra resistance from flapping straps. There's also a chin strap pad but this is removable so I got rid of it quickly.

Planet X Carnac Kronus Time Trial Helmet.jpg

Protecting your eyes is a very large visor. This comes in clear as standard but there are four other tints to choose from, each costing £39.99. The visor is held in place by magnets. They were very effective, holding strong on some rough training lanes. I didn't get too much fogging, possibly owing to the large gap between the lens and my face.

Planet X Carnac Kronus Time Trial Helmet - visor going on 2.jpg

In the breathability department, this helmet is excellent. My head was no sweatier than usual, although I am used to criterium racing in a relatively unvented Lazer Z1 with Aeroshell. I did have a little river of sweat running down the inside of my lens, but I feel that's unavoidable.

At 395g, it's roughly on par, if a touch heavier than the similar Kask Bambino, but with the Kask costing nearly three times the price, I'd be hard pushed to look past the Carnac Kronus. And to be honest, I'm struggling to find a better deal for a time trial helmet. If you're looking to shave off a little time from your 10-mile or 25-mile personal best, this is an inexpensive and comfortable helmet that should provide an aero edge over your standard road lid.

Planet X Carnac Kronus Time Trial Helmet - inside.jpg


Aero, comfy and cheap, one of the best time trial helmet deals going

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Make and model: Planet X Carnac Kronus Time Trial Helmet

Size tested: 58-62

Tell us what the product is for, and who it's aimed at. What do the manufacturers say about it? How does that compare to your own feelings about it?

From the PlanetX website:

"Designed with our sleekest aerodynamic profile yet Carnac's Kronus Time Trial and Track Helmet will facilitate shaving seconds off your times and protect you from those inevitable racing incidents. With a sleek frontal profile, it helps you slice through the wind and it's so adjustable and lightweight that you're sure to be able to find your perfect fit.

A wide field of view is provided by a replaceable Tru-Sight visor made from optically clear polycarbonate and profiled to offer maximum clarity with reduced peripheral distortion. Held in place by high power Neodymium magnets you can quickly swap between different lenses choosing the right lens colour and light transmissivity for the lighting conditions.

As well as keeping you cool with 6 strategically placed, front facing slit vents the Carnac Kronus Helmet provides outrageous comfort. Our Occipital Cradle is fully adjustable for width and height. A 70mm width adjustment range coupled with a 12mm of height adjustment and our anti-bacterial treated soft pads ensure the widest possible range of adjustment.

Built using our proven single-shot construction, a full coverage EPS core is co-moulded over the fittings that anchor the straps and occipital cradle into the body of the helmet for maximum durability. If you're looking to accrue marginal gains to improve your performance a brilliant aero helmet can save you watts and precious seconds on every ride."

This is a full time trial helmet. I'd say that you could also use it on the track, just at Planet X suggest, but you could also use this for triathlons (the bike part, not the swim, obviously).

Tell us some more about the technical aspects of the product?

From PlanetX website:

"Minimum drag with integrated ventilation

Tru-Sight, Magnetically fixed visor. Clear lens included.

Perfect Fit, 3-way adjustability

Removable, anti-bacterial treated comfort pads"

Rate the product for quality of construction:

The padding is comfortable, the magnets work well and the helmet feels very secure. They could possibly have shrunk the exterior profile to make this a smaller lid, but maybe this is all to do with aerodynamics....

Rate the product for performance:

I can't make any aero claims and Carnac don't state any. It felt fast anyway.

Rate the product for durability:

I had no issues with any wear, but as a time trial lid, it was only really used on race days.

Rate the product for weight (if applicable)

It's not as light as the Kask, but there's got to be some compromise for £200 less.

Rate the product for comfort (if applicable)

Not the biggest range of vertical adjustment, but it was sufficient to get a comfortable fit.

Rate the product for value:

I'd bet it's less aero than the Kask, but how much are you willing to pay to save a few watts?

Tell us how the product performed overall when used for its designed purpose

I found it comfortable and not overly sweaty during my local evening 10-mile time trials

Tell us what you particularly liked about the product

The price is brilliant when compared to similarly shaped helmets

Tell us what you particularly disliked about the product

The size of my large was a little too large. But that might suit other more.

Did you enjoy using the product? Yes

Would you consider buying the product? Yes

Would you recommend the product to a friend? Yes

Use this box to explain your score

At a third of the price of a similar Kask Bambino, this has to be one of the best deals going. Only loses half a star for being a little large on the head.

Overall rating: 9/10

About the tester

Age: 22  Height: 177cm  Weight: 64kg

I usually ride: Cannondale Supersix Di2  My best bike is:

I've been riding for: 5-10 years  I ride: Every day  I would class myself as: Expert

I regularly do the following types of riding: road racing, time trialling, cyclo cross, commuting, club rides, general fitness riding, I specialise in the Cafe Ride!

Add new comment


mtbtomo | 387 posts | 5 years ago
1 like

Doesn't look any sweatier than my Kask that cost a lot more.  Not many TT helmets prioritise air vents and cooling.


I bet it's similar enough to my Kask aero performance wise too, and I would have saved my money buying this had it been out at the same time.

Simboid | 139 posts | 5 years ago

Looks unbelievably sweaty. At least there are not many parts to fall to pieces, like everything Planet X make.  I'll bet you can find exactly the same thing on Alibaba even cheaper if budget aero is your thing.

fenix | 1452 posts | 6 years ago
1 like

The best helmet for aerodynamics is very personal.  What works for one person may not work for the next.


So unless you've hours to play with and a velodrome and powermeters and all the helmets to test - or a wind tunnel and similar - you'll just have to use your own judgement. 



check12 | 691 posts | 6 years ago

"Aero, comfy and cheap, one of the best time trial helmet deals going"

I don't see any aero data in this review? It looks like a kask but is it similar aero wise? I recall Xavier aero coach chap saying people who turned up in a kask usually found a better aero helmet. 

DavidC replied to check12 | 162 posts | 6 years ago
1 like
check12 wrote:

"I recall Xavier aero coach chap saying people who turned up in a kask usually found a better aero helmet."

Anyway, "improved aerodynamics" between models can be a case of splitting very tiny hairs. A few months ago I considered buying a Giro Aerohead, but changed my mind after seeing Giro's marketing (which doesn't seem to be on their site now).

By Giro's own calculation, compared to my existing, rather old aero helmet, the Aerohead is barely an improvement (not even close to 1%, if you take Giro's interpretation of the data at face value), and this is a tiny improvement for only the helmet, not the full rider and bike package.

So, I expect the difference between this model and the Kask to be less than huge.

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