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Louis Garneau Diamond II Helmet

Sale $94.97 $189.95 50% off

Item # LGN0913

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  • Black/Yellow, S ($94.97)
  • Black/Yellow, M ($94.97)
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Item # LGN0913

The more vents, the better.

It's true, we're starting to see an industry trend that's leading away from helmet ventilation in favor of aerodynamics. However, the question begs to be asked, 'what are you willing to give up for marginal gains?' And while we're a fan of free speed and innovation, in our books, ventilation is king. Not surprisingly, Louis Garneau agrees, and its new Diamond II Helmet takes this idea and rides away with it.

In fact, we detect a slight hint of one-upsmanship. While the industry overkill of ventilation has for years been dominated by the Whisper Plus' 39 vents, the Diamond II features 40 and weighs in around a svelte 285 grams. And on top of this, the Diamond II met all North American certifications right out of the gate. So, you can be assured that increasing safety is still the paramount feature of this helmet. So, how did Garneau do it? Its patented Super MSB (Monocoque Structural Base) and EXI technologies, of course. Basically, these two designs work in unison to eliminate the commonality of rib construction in helmets. As Garneau puts it, the prior means of manufacturing adds weight and minimizes the amount of potential ventilation, all the while without increasing safety. And while all of that sounds pointless and archaic, the solution was complicated from engineering standpoint.

The path to the Diamond II took a few steps. The Super MSB structure is basically a supportive base that's akin to an exoskeleton. It has a polycarbonate, monocoque construction, meaning that it's formed in one piece. This reinforces the perimeter of the helmet, while supporting the EXI-insert with confidence -- and this is where the rib-replacement comes into play. Together, the two systems position two polycarbonate bars within the helmet structure, with an additional nine carbon fiber bridge inserts. The system provides targeted structural support to the helmet in the case of collision. For further reinforcement, the entire structure is created with In-Mold construction. This means that the helmet's shell and foam liner are molded together at the same time.

With Garneau's new structural design, it was able to increase the ventilation without degrading strength. But Garneau wasn't finished with the Diamond II's comfort. The helmet features what Garneau calls its Evacuation Channels. These ports in the helmet provide an increased airflow over the head, while creating a dispersion of internal moisture. To secure the helmet, Garneau incorporated its Spiderlock PRO II stabilizing system that permits one-handed adjustments to the helmet's retention. It also has a polymer neck support and an anti-slip turn-wheel for precise and secure adjustment. At the chinstrap, the Diamond II comes equipped with cam-locking device that simplifies the process of dialing-in the helmet's fit. And lastly, Garneau also included X-static XT2 padding internally for its antimicrobial, comforting support.

And as if a helmet wasn't enough protection, the Diamond II features a reflective decals and a Spiderlock Vision light that fits over the stabilizing wheel at the rear of the helmet. So, your visibility is effortlessly increased to passing motorists in low-light conditions.

The Louis Garneau Diamond II Helmet is available in the sizes Small, Medium, and Large and in the colors Black, Red, and White Customizable.

  • In-mold polycarbonate construction
  • Super MSB frame
  • Carbon-fiber bridge inserts
  • Plastic EXO inserts
  • Spiderlock Pro II dial fit adjustment
  • X-Static XT2 antimicrobial padding
  • 40 vents
  • Reflective detailing

Tech Specs

Shell Material:
40 vents
Fit Adjustment:
Spiderlock Pro
Claimed Weight:
285 g
Recommended Use:
Manufacturer Warranty:
1 year

Size chart

Fuji Bicycles


Geometry Chart


Altamira LTD

Seat Tube


Effective Top Tube








Head Tube


Head Tube Angle


Seat Tube Angle


Bottom Bracket Drop


Chainstay Length



44 44.0cm 51.5cm


36.3cm 72.1cm


72.0 deg 75.0 deg 6.9cm 40.5cm 97.1cm
47 47.0cm 53.0cm


37.0cm 74.1cm 13.0cm 72.5 deg 74.5 deg 6.9cm 40.5cm 97.7cm
50 50.0cm 54.5cm 54.0cm 37.0cm 76.0cm 14.0cm 73.0 deg 73.5 deg 6.9cm 40.5cm 97.6cm
53 53.0cm 56.0cm 56.0cm 37.9cm 78.3cm 16.0cm 73.5 deg 73.5 deg 6.9cm 40.5cm 98.6cm
55 55.0cm 57.5cm 58.0cm 38.9cm 80.1cm 18.0cm 73.5 deg 73.5 deg 6.9cm 40.5cm 100.1cm
58 58.0cm 59.0cm 60.1cm 39.7cm 82.1cm 20.0cm 74.0 deg 73.5 deg 6.9cm 40.5cm


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Here's what others have to say...


Great Fit

  • Familiarity:I've used it several times

Well ventilated and easily adjusted for a good fit.


Well done

    Good looking in all colors, carbon fiber bridge inserts, very well ventilated, X-static pads, very good Dial closure system (IMO at least as good as Giro's). Good price.

    The white comes with stickers in multiple colors (red, blue, yellow) to customize the look. Cool.