The Bell Z20 Aero MIPS helmet bridges that balance between aerodynamics and the ventilation of a normal road helmet. It's comfortable to wear and comes with the added benefits of the MIPS system, though it is pretty expensive.
If you are a time triallist or triathlete, aerodynamics take priority over pretty much all else on the bike, but for a roadie who wants a bit of that wind-cheating help then some compromises have to be weighed up.
Ventilation is the key factor, and Bell certainly knows what it's doing here with the Z20. Even on helmets with 20-odd vents it still comes down to where you position them rather than just the amount or size of the holes.
The Z20 has just 10 vents split evenly between the front and rear. Bringing in the air is the large central channel that sits just above your forehead, with one more either side which are then separated by a structural rib.
You can really feel the cool air flow in as you are riding, quite dramatically. I was very impressed when riding on one of the hottest days of the year to still feel pretty fresh, as the colder air replaced the warmer stuff as it travelled out through the rear exhaust vents.
The only time it does become a touch toasty is on long climbs in the heat, but that is to be expected.
Looking at its construction, the Z20 is made up of two parts bonded together, the internal structure being no doubt that of the standard Z20 MIPS with all of the vents already cut out but with an EPS (expanded polystyrene) cover section, itself covered with a polycarbonate outer shell.
It does add some depth to the front of the helmet with its two layers of EPS, which I did notice in my eyeline a few times – especially when looking up the road from a crouched position – but it's not enough to really affect your vision.
Surprisingly, though, this extra material hasn't added much to the overall weight, with this medium size weighing in at 279g. Impressive for a standard helmet but even more so for an aero offering.
Dealing with fit and adjustment is Bell's Float Fit Race, which is adjusted by a dial ratchet system at the rear. Nothing unusual about that, but it's good to see that this cradle runs right the way around the helmet so when tightening you get an even tensioning right the way around your head. Some helmets only adjust the rear half.
The height of the helmet in relation to the cradle can be adjusted to four different positions too.
Between the cradle and the EPS you'll find a MIPS layer, which is becoming more and more commonplace on cycling helmets. It stands for Multi-directional Impact Protection System, and is basically a slip-plane. Strategically placed tabs connect the two parts of the helmet intended to reduce rotational forces during impact, allowing the cradle to move independently of the helmet by a small margin. (Read more here.)
The padding inside isn't massively thick, but I found it perfectly comfortable and it doesn't get too overwhelmed with sweat either. The padding contains silver fibres to inhibit the growth of bacteria.
It comes in a range of six colours and three sizes: small, medium and large.
At £209.99 it is quite a pricey lid, even with the Mips technology, which is showing up on helmets from as little as £69.99, like the Giro Isode.
Aero goodies often incur a higher price, but the Bell is still 20 quid more than the Giant Pursuit MIPS Aero. The Z20 is a lot lighter, though, and has better ventilation.
Even Specialized's Evade helmet will 'only' set you back £200, and it's around 30g lighter overall.
On the whole, though, the Bell is a decent choice if you want the wind-cheating properties of an aero lid but don't want to overheat on all but the steepest of climbs.
Surprisingly breathable, lightweight aero helmet but it's priced at the top end
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road.cc test report
Make and model: Bell Z20 Aero MIPS helmet
Size tested: Medium
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?
Bell says, "Every watt counts. The Z20 Aero is built with that in mind, delivering uncompromising performance, innovation, fit and comfort. With its drag-defying shape, Progressive Layering, and Integrated MIPS, this helmet provides real-world performance for riders who want to lead."
It's a decent performing lid with a good balance of aerodynamics, comfort and ventilation.
Tell us some more about the technical aspects of the product?
Bell lists these features:
FUSION IN-MOLD POLYCARBONATE SHELL - A PROCESS PIONEERED BY BELL BONDS THE HELMET'S OUTER SHELL TO THE EPS FOAM LINER TO CREATE A STURDIER HELMET.
PROGRESSIVE LAYERING: THE PROCESS OF ENGINEERING A HELMET LINER WITH VARIABLE EPS FOAM DENSITIES TO BETTER MANAGE THE TRANSFER OF ENERGIES AFTER SOME IMPACTS
NO-TWIST TRI-GLIDES: QUICK-ADJUST FASTENERS THAT HELP KEEP STRAPS FLAT AND PROPERLY POSITIONED
FLOAT FIT RACE - A STATE-OF-THE-ART LIGHTWEIGHT FIT SYSTEM FEATURING SEAMLESS INTEGRATION WITH MIPS, AN EASY-TO-TURN DIAL, WIDE-RANGE VERTICAL ADJUSTMENT AND PADDED WIDTH-ADJUSTABLE CRADLES
OVERBROW VENTILATION FEATURES INTAKE PORTS ON THE BROW OF THE HELMET TO USHER IN COOL AIR AND PUSH IT THROUGH THE AIR-CHANNEL MATRIX FOR FULL-HEAD VENTILATION
SWEAT GUIDE PAD DESIGN PULLS MOISTURE AWAY FROM THE BROW PAD AND AWAY FROM EYEWEAR
X-STATIC PADDING - QUICK-DRYING MATERIALS, WOVEN WITH REAL SILVER FIBERS, INHIBIT GROWTH OF ODOR-CAUSING BACTERIA AND FUNGI
MIPS®-EQUIPPED - MIPS STANDS FOR MULTI-DIRECTIONAL IMPACT PROTECTION SYSTEM, WHICH IS A LEADING SLIP-PLANE TECHNOLOGY INSIDE THE HELMET DESIGNED TO REDUCE ROTATIONAL FORCES THAT CAN RESULT FROM CERTAIN IMPACTS.
Tell us how the product performed overall when used for its designed purpose
I can't verify its aero performance, but for an enclosed helmet with minimal venting it breathes well and is comfortable to wear.
Tell us what you particularly liked about the product
Tell us what you particularly disliked about the product
Bulky front end can get in your eyeline a bit.
How does the price compare to that of similar products in the market, including ones recently tested on road.cc?
It's at the top end, even against some of the most expensive aero helmets.
Did you enjoy using the product? Yes
Would you consider buying the product? Possibly
Would you recommend the product to a friend? Yes
Use this box to explain your overall score
Overall, the Z20 Aero is a quality helmet, but just a few niggles and the price keep the overall mark down.
About the tester
I usually ride: This month's test bike My best bike is: B'Twin Ultra CF draped in the latest bling test components
I've been riding for: Over 20 years I ride: Every day I would class myself as: Expert
I regularly do the following types of riding: time trialling, commuting, club rides, sportives, fixed/singlespeed
With 20 years of road cycling and over 150,000 miles in his legs it's safe to say Stu is happiest when on the bike whatever the weather. Since writing his first review for road.cc back in 2009 he has also had a career in engineering including 3D-CAD design and product development, so has a real passion for all of the latest technology coming through in the industry but is also a sucker for a classic steel frame, skinny tyres, rim brakes and a damn good paintjob.
His fascination with gravel bikes is getting out of control too!