Gemini Iris Rear Light

Gemini's Iris rear light claims to pump out a retina-melting 180 lumens of red. That's enough to get you seen in any conditions, and there are plenty of lower-power modes for general riding too. And it's well made.

First things first: ye gods, this thing is bright. You know when you turn a light on, and you think, "MY EYES!"? Well I did that with the Iris, only to find out it wasn't even on the brightest setting.

> Find your nearest dealer here

> Buy this online here

In fact, it wasn't even on the second-brightest setting. Seriously, this is one bright rear light. I think I can safely say it's the brightest rear light I've ever fitted to my bike. It's positively nuclear on its top power. I haven't ever used that setting out on the road, for a couple of reasons. Firstly, I've been using the light at night, when it's more light than I think I'd ever need, unless I was venturing out onto a trunk road or something. Secondly, you'll suck the battery dry in about an hour.

So why even have it, then? Well, if I were to head out to an evening time trial in the summer on a fast (read: busy) course, it's exactly the kind of light output I'd want. You can probably see it from a mile away in broad daylight. And for a 10, or even a 25, it'll go the distance. Assuming your 25 goes well...

There's more to the Iris than full nuclear, though. It has two different flash settings, and five different power levels, and you can program the light to use the power levels you want. You get to choose from 10, 30, 50, 100 and 180 lumens. For most riding I found the 10-lumen setting to be more than adequate, and you get the best part of a day of light on pulse mode (the more-off-than-on flash setting). For daytime running, 50 lumens in pulse mode gives you 8hrs of run time and left me thinking that I'd get seen even on quick roads. The brighter settings, and the more intense flash mode, mean shorter run times that might not last a club run.

Talking of club runs, I expect you're wondering if there's a group-friendly constant option... The answer, if you were to read the instructions, or go to the Gemini website, is no: there's no mention of one. But it is there, hidden away. Press the power button for six seconds and you can cycle through the power levels on constant. Mostly I used that for chaingangs and rides with friends, and the 10-lumen low-power level was good for more than 8 hours, with higher power knocking down the battery life considerably. The power button serves as a visual indicator of the power level, giving you a decent warning that the lights are going to go out.

Mounting is simple enough. There's a seatpost mount (really only suitable for a round section post) and the light fixes on with a chunky silicone O-ring. The light tends to point down a bit, but that's pretty good because it lights up the rear tyre and the road behind you, and doesn't point directly into the eyes of anyone behind you, which they wouldn't thank you for. There's a clip for bag-mounting too.

Charging is via a Micro-USB socket and the 900mAh Li-Ion battery takes a couple of hours to fill back up. The port is covered by a rubber flap that needs a bit of attention to make sure that it's snugly fitted, but I've not had it pop off during a ride and the light has seen some pretty dismal conditions with no water getting inside.

> Check out our guide to the best rear lights here

It's a nicely made light: the aluminium body gives it a quality feel, and it's survived a few knocks with only the odd scratch. The downside to the recessed lens is that it can collect mud on mucky lane rides, and the Iris doesn't have the kind of side visibility that you get from a rear light with a translucent body, so it's not quite as obvious around town as something like a Cateye Rapid X.

Although £60 is a lot for a rear light, if you're looking for one that will offer top-class long-range visibility on fast roads, and in daylight, this should be near the top of your list. If you're going to use the Iris as more of an all-rounder then lower modes preserve the battery life and they're more than enough light for nearly anything. The lack of side visibility marks the Iris down in the overall safety stakes, but the build quality means it's a light that should last. Overall, it puts in a very good performance and it's a light I've been happy using as a single rear for all kinds of riding.

Verdict

Top-of-the-class brightness for when you really need to get seen, with a good range of lower power options