Giro Synthe MIPS II helmet review

The updated Synthe comes with a lower price than the original due to its use of a superseded type of MIPS, but as the 'UItegra' of Giro's range it is still a high-performance road helmet

Giro Synthe MIPS II
(Image credit: Simon Smythe/Cycling Weekly)
Cycling Weekly Verdict

It's not often that an updated, improved version of helmet is priced lower than the original, but this is the case with the Giro Synthe MIPS II. This is because it uses what has become entry-level MIPS - the slip plane type - now that Giro is speccing its latest Spherical MIPS on its flagship road helmets the Eclipse and Aether. However, if you're not bothered about having the latest MIPS protection system and are looking for a comfortable, well vented, classic-looking road helmet the Giro Synthe MIPS II could be for you.

Reasons to buy
  • +

    Very comfortable

  • +

    Classic looks

  • +

    Updated integrated MIPS (though not the flagship Spherical type)

  • +

    Lower price than the original

Reasons to avoid
  • -

    Wide look might not suit narrow faces

The original Giro Synthe launched in 2014 and was one of the most advanced pro-level helmets (opens in new tab)at the time. It was comfortable, well ventilated, aerodynamic, lightweight, slimline and strong with Giro’s Roll Cage reinforcement.

Giro calls it an ‘icon’ - justifiably. So how to improve on it?

Giro Synthe MIPS II: construction

Giro Synthe MIPS II top view

(Image credit: Simon Smythe/Cycling Weekly)

The Giro Synthe MIPS II keeps the same classic 'hand of bananas' shape but is, according to Giro, updated to be lighter and more comfortable than ever before.

How has this been achieved? The Synthe II no longer has the polycarbonate mesh panel that filled one set of side vents, enabling improved airflow through its 10 vents. This also gives it a cleaner look but Giro doesn’t claim any aero improvements.

Giro Synthe MIPS II

(Image credit: Simon Smythe/Cycling Weekly)

The Synthe MIPS II uses a newer integrated MIPS (multi-directional impact protection system) than the original so that the plastic slip plane is now combined with Giro’s Roc Loc 5 closure.

Giro doesn’t reveal how the weight has been lowered and by our measurements the original Synthe was actually lighter.

Giro Synthe MIPS II rear view

(Image credit: Simon Smythe/Cycling Weekly)

Either way, we’re only talking grams and it’s certainly not a big deal: Giro’s very latest pro-level helmet, the Eclipse Spherical (opens in new tab), has a claimed weight of 275g, which is a gram heavier than our size M Synthe MIPS II (actual weight).

Something indisputably lower is the price. In 2017 when we included the original Synthe in our Editor’s Choice roundup of the year’s best kit it cost £249. The new version has an RRP of £179. 

The lower price reflects that the Synthe II doesn't use the more sophisticated Spherical MIPS of the Eclipse, Aether and Helios. Spherical MIPS dispenses with the slip liner since it consists of two shells that slip against each other, often compared to a ball and socket.

However, the Synthe II still compares very favourably to its more expensive siblings.

The ride

Thanks to the integrated Roc Loc 5 Air MIPS cradle, and probably due to the shape of the helmet itself too, comfort is very impressive. Helmet fit is a personal thing, but I’ve always got on well with Giro helmets. Some say Giro helmets suit rounder heads, but mine is more oval and since the days of the Pneumo 20 years ago I’ve found Giro road helmets to supply a glove-like fit.

If you've got on well with the fit of Giro helmets in the past, you'll get on well with the Synthe MIPS II.

The straps are easy to adjust for correct spacing around the ears. Giro's standard straps and plastic hardware are specced here.

Giro Synthe MIPS II front view

(Image credit: Simon Smythe/Cycling Weekly)

A custom touch, however, is the additional of small rubber grippers at the entrance to the front/side vents which work as what some helmet manufacturers call an ‘eyewear dock’. These work really well and - as with Giro helmets of the past - the vents are exactly in the right place for sticking your sunnies in.

This helmet was only launched last November so I can’t verify Giro’s claims that it’s better vented than the original, but the 19 vents do let air rush in easily and I’d say there won’t be a problem with overheating in warm weather. Before he was famous Ollie Bridgewood tested the original Giro Synthe (opens in new tab) for CW in Majorca on the Sa Calobra climb in 25 degrees and reported that the only discomfort was in his legs.

The only thing I’m not quite convinced by is the shape of the Giro Synthe II MIPS. I don’t have the original one here to compare it to so I can’t say for sure that it is more flared than it used to be, but it now looks wide compared to other modern road helmets, certainly wider than equivalent sizes in the Giro Helios (opens in new tab), HJC Furion and Abus Gamechanger (opens in new tab) - my three regular helmets. I prefer a lower-profile helmet as I have a longish head that can easily appear mushroom shaped with a helmet that’s too wide sitting atop it, so if you’re the same it’s worth trying one on first and looking in the mirror.

To be clear, this doesn't affect the excellent fit - it's just the shape of the shell.

Value and conclusion

As I've mentioned, this latest iteration of the Synthe uses what has become entry-level MIPS now that Spherical MIPS is here, and for that reason the price has dropped from £249 - the RRP of the original Synthe - to £179.

MIPS aside, Giro has tweaked the performance of the Synthe II so that now it's better ventilated, more comfortable with its (cheaper) integrated MIPS and its weight matches that of the flagship Giro aero helmet, the Eclipse.

The wider look might not suit those with narrower heads - though once again to be clear that's just the looks rather than the fit, which is superb.

The Giro Synthe II MIPS might now be the Ultegra of Giro road helmets, but as we all know, that's where you get the performance without the price tag.

Giro Synthe MIPS II specs
Integrated MIPS® brain protection system
Featherweight webbing with Slimline™ buckle- Ionic+™ anti-microbial padding
In-Mold polycarbonate shell with EPS liner
Thermoformed SL Roll Cage™ reinforcement
Roc Loc® 5 Air Mips
19 Wind Tunnel™ vents with internal channeling
S 20”–21.75”/51–55cm, M 21.75”–23.25”/55–59cm, L 23.25”–24.75”/59–63cm
Complies with the US CPSC Safety Standard for Bicycle Helmet for Persons Age 5 and Older
Weight (size M): 274g

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