Bell Z20 Aero MIPS helmet

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.

• Pros: Good airflow; comfortable padding and fitting system
• Cons: Feels bulky at the front; pricey

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.

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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.

> Keeping your helmet clean, and other bike kit bio-hazards

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.

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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.

> Should you buy an aero helmet?

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.

Verdict

Surprisingly breathable, lightweight aero helmet but it's priced at the top end