Sunglasses for motorcycle riding: wind, impact and the helmet decide more than the tint

On a motorcycle the lens tint is the last decision, not the first. Before it come three things that decide whether a pair is usable at all: the frame has to fit under a helmet without the temple arms pressing, it has to seal well enough that wind at speed does not dry your eyes and drive grit into them, and the lens has to survive a stone thrown up by the vehicle in front. Only then does the tint matter, and the answer there is a medium brown or grey polarized lens, never a dark one, and never a dark one under a tinted visor. A helmet visor does part of this job and sunglasses do the rest; which part depends on the helmet.

Priority one: under the helmet

Full-face and open-face helmets both press on the sides of the head where temple arms sit. A frame with thick or curved arms either will not go on with the helmet, or presses into the temples until it aches. Riding sunglasses have thin, straight arms for this reason.

Test it: put the helmet on first, then slide the sunglasses in. If the arms have to be forced, or you feel pressure at the temples within a minute, they are the wrong frame for that helmet. Our headache post explains why that pressure becomes a headache.

Our T01 has plastic arms of ordinary thickness. Under an open-face helmet it goes on; under a snug full-face it depends on the helmet, and we would not promise it.

Priority two: wind

At town speeds, an ordinary frame is fine. Above about 50 km/h, wind around the edges of a flat frame dries the eye in minutes, makes it water, and carries grit and insects into it. Riders with open frames end up squinting, which defeats the point.

Two fixes, and most riders use both:

• A visor. A full-face helmet's visor, or a flip-down visor on an open-face, seals the wind. Sunglasses then handle the light behind it.
• A frame that seals. Riding goggles, or wrap sunglasses with a foam gasket, seal against the face. They fog when you stop, which is the trade; our fogging post explains it.

A flat frame like our T01 behind a visor is a fine combination. A flat frame alone at highway speed is not.

Priority three: impact

A stone off a truck tyre at highway speed hits hard. Glass lenses can shatter into the eye and have no place on a bike. Polycarbonate is the standard because it is the toughest common lens material; tri acetate cellulose, which ours is, flexes rather than shatters but is not as tough as polycarbonate. Our lens materials post compares them, and our safety ratings post explains what a stated impact rating actually tests.

Riding eyewear is often tested to an impact standard and says so. Everyday sunglasses, ours included, are not, and we do not claim otherwise. Behind a visor, which is itself impact-rated, that matters less; on an open-face helmet without a visor, buy eyewear that is rated.

Then the tint

Medium, not dark. A road passes through sun and shade, under bridges and into tunnels, and on a bike you cannot lift a lens with one hand. A medium lens is right for the sun and survivable in the shade. A dark lens leaves you blind for the seconds after every tree line.

Brown for contrast on tarmac and in changing light. Grey for true colours in flat bright sun. Both polarized, for the glare off the road and off car glass. Our driving lens post covers the choice, and the same logic applies on two wheels with less margin.

Never stack. A tinted visor plus a dark lens is a very dark lens, well into the category that road authorities say must not be used for driving. Our lens categories post explains the bands. Clear visor with sunglasses, or tinted visor with clear glasses, not both.

Polarized and the dashboard. Many bike instruments are LCD, and some go dim through polarized lenses at certain angles. Sit on the bike and check before you ride; our screen post explains what you are seeing.

The order, again

1. Fits under the helmet.
2. Wind is handled, by a visor or a sealing frame.
3. Lens will not shatter.
4. Medium brown or grey, polarized, and not stacked under a tinted visor.

Frequently asked questions