Reviewed by Brian Mullin http://www.gramslightbikes.com/
I have been putting the Julbo Dirt sunglasses through the paces from close to a year now while mountain biking. They have dealt with wind storms, rain, snow, and light varying from the bright desert, to the dark woods, and everything in between. They have gotten bounced around while riding through rock gardens, ridden at Mach 1, been dropped on the ground a number of times and been worn under assorted helmets (even full face). They have turned out to be comfortable, durable, fog free, and offer excellent wind protection, great varying light capabilities and superb optical clarity.
Julbo was founded in 1888 by Jules Baud in a little town close to Morez France, which resides in the Jura Mountains. The company has 70 employees, and is wholly owned by the Baud family, and is currently run by the brothers Christophe and Matthew. They originally started out making optical (corrective) lenses, but they evolved into sunglasses and action sports wear. In 1950 Julbo was the first company to produce true mountaineering glasses (the Vermont Round), so they have a rich history in high altitude optics.
The Julbo Dirt is a bit of a departure from the average sports eyewear, and instead of the atypical thin or skinny frame, its built beefier, with a very wide section by the hinge and temple, which offers additional side protection from sunlight. The hinged wraparound frames have a nice sculptured curve, and has soft rubber shock absorbing material for the nose and ears, offering grip while doing athletic movement. They mainly come with the Zebra lens made from the indestructible NXT, which offer anti-fogging, impact resistance and light-sensitive Photochromic features. They also comes with a nifty hard case to carry, and protect them. The Dirt come in several versions and colors, the Zebra (NXT, Photochromic 2-4, Antifog) in White, Black, and Chocolate, the Camel (NXT, Polarized, Photochromic 3-4, Antifog) in Khaki and the Polarized 3 in black. If it’s required, you can order them with corrective lenses.
Weight: 40 grams (1.4 ounces)
Lens size: 65mm x 40mm (2.5 x 1.5 inches)
Arm Length: 71mm (4 3/4 inches)
Frame Width: outer 145mm (5 3/4 inches) inner 130mm (5 1/8 inches)
Zebra Photochromic Lens
The Dirt’s use Julbo’s Zebra photochromic lens made from the unbreakable, lightweight and very transparent NXT. They quickly darken with a light brownish tint or lighten with an amber tint depending on light intensity, and have an anti-fog coating that has been laser etched into them. Per Julbo fodder “adapts to varying light conditions from Category 2 (59-percent visible light coverage) in low light conditions to Category 4 (95-percent visible light coverage) in powerful light in as little as 30 seconds”.
The NXT polymer technology was born of the successful efforts to develop advanced transparent armor for U.S. Army helicopters. Commercial applications for the new transparent polymer material led to the production of lenses and shields for sunglasses and sport eye wear. The NXT lens is manufactured by pouring resin into a low-temperature glass molds. This reduces the tension in the material and gives better optical quality, excellent transparency and improved long-term stability. The NXT lens meets the ANSI Z87.1 standard for industrial application impacts, meaning it must withstand a pointed 17.6 ounce projectile dropped from a height of 50 inches, and 1/4 inch steel ball traveling at 150 ft/sec! I did not test either compliance, but I am glad it can take a wallop. Julbo lenses offer 100% protection against UVs: UVAs, UVBs, and UVCs.
For some in-depth fodder on Sun and Eyes, refer to http://reviews.mtbr.com/blog/sunsunlight-101-and-human-eyes-101/