Rudy Project Deltabeat Light Grey Impactx Photochromic 2 Black

The Rudy Project Deltabeats may not compete with the unobstructed viewing experience large frameless sunnies provide, but the top-quality photochromic lenses adjust to changing light conditions effectively, as well as providing protection from wind and flicked-up dirt. The sturdy feeling frame uses a bio-based polyamide, reducing the Deltabeats' carbon footprint as well as delivering good ergonomics.

The Deltabeat sunnies have a wraparound frame made from Rilsan Clear, which is a bio-based polyamide produced from castor bean oil grown in the Gujarat region of India, and then developed by Arkema.

'The beans are crushed to produce castor oil and the oil is further refined during several steps to produce the primary bio-based raw material in the polymer,' Rudy Project explains. Rudy Project has adopted this bio-based material as a sustainable alternative to Grilamid TR90, a material commonly used for sport sunnies, which it says has much of the same properties. It's certainly a strong and sturdy material that feels as though it could withstand regular use, and so it's great to see an eco option chosen here.

> Buy these online here

A photochromic lens helps to deal with varying light conditions – which are typical for most UK riding. Either it's clouds intermittently obscuring or revealing the sun, or shady forested roads giving way to wide, open – and bright – fields. With the lens automatically darkening and clearing to suit the light conditions, you can get on with your ride without squinting through glare or picking your way down an artificially darkened descent.

Although the photochromic version is more expensive at £128.74 compared with £98.68 for standard lenses, it's arguably better value as it covers you for both dark and bright rides – not to mention being more convenient than continually swapping between lenses depending on light conditions.

Rudy Project's photochromic lenses are available in four options; I had the ImpactX Photochromatic 2 Black on test, which offer a huge light transmission range of 74% to 9% – essentially, clear to really quite dark.

Even though there's less need to switch out the photochromic lenses, if you wanted to, I found it was a quick and straightforward process.

Far from the oversized styling of some shades, such as the SunGod Airas, the lens height is just 51mm and each side measures 69mm. Despite the smaller size, the lenses sit close across your face, which effectively seals out those eye-watering gusts.

To minimise misting, Rudy Project has its PowerFlow ventilation solution, which consists of a vent on the top outer edge of each lens and the inner bottom edge, as well as vents at the front of the frame, on the inside by the nosepiece and along the arms to adjust the airflow. These do a very good job at holding back the fog-up. It was only when I stopped at the top of a hill after an unpleasant effort that misting did start to appear, which is not a surprise. During actual riding I had no such issues, it's very effective.

The ErgoNose system is very good. It's an adjustable nosepiece that allows you to fine-tune the fit to one that's both comfortable and secure. While it can take a little longer than swapping in different sized nosepieces, I found I was able to dial in the fit I preferred. It bends into the shape you want and doesn't shift when you're riding.

The frame arms naturally curve inwards and while there is a reasonable amount of flexibility to them, in my experience the slim arms would still dig in slightly – which over the course of a two-hour ride could become a little uncomfortable.

Other than that, the fit and security of the glasses is great. I found they stayed put throughout sweaty outings or prolonged rain, as well as rides on rougher terrain.

Value

Priced at £128.74, the Deltabeats are pretty good value. I recently tested SunGod's Airas BF with a photochromic lens which are much more expensive at £195, and the Zero-Frame option is also high at £170. You do benefit from plenty of customisation and greater coverage from a larger lens, though.

> Buyer’s Guide: 10 of the best cycling sunglasses

That's not to say the Deltabeats are the most affordable photochromic option out there. The BZ Optics TOUR Photochromic Glasses HD Lenses offer excellent clarity and a snug fit, for £94.99, although a fair amount of the frame is in your eyeline. dhb's Vector sunnies are just £90 and consist of a frame at the top, which is amazingly unobstructive.

Conclusion

Overall, the Deltabeats are a very solid choice if you're looking for a quality photochromic lens option that offers good protection from both roadside debris and gusty winds. Its frame feels robust and even boasts eco credentials, being made from a bio-based oil. The only negative for me was that although the nosepiece provided good adjustment and was highly comfortable, I did find the arms could dig in a little on longer rides.

Verdict

Very good high-quality shades with a new bio-based frame