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Cateye Rapid X3 rear light



Fantastic all-round visibility from a neat package, though you won't get 100 lumens for long

At every product is thoroughly tested for as long as it takes to get a proper insight into how well it works. Our reviewers are experienced cyclists that we trust to be objective. While we strive to ensure that opinions expressed are backed up by facts, reviews are by their nature an informed opinion, not a definitive verdict. We don't intentionally try to break anything (except locks) but we do try to look for weak points in any design. The overall score is not just an average of the other scores: it reflects both a product's function and value – with value determined by how a product compares with items of similar spec, quality, and price.

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Bigger and much brighter than previous Rapid X models, the new Cateye Rapid X3 rear light kicks out such a potent red glow on full power that you might think you could warm your hands on it. As with previous models from this range, it has outstanding visibility from the sides as well as from behind, making it a top choice for the busy urban environment. It's pricey, though, and you'll want to use the full-power mode sparingly if you're going far.

Last year's Rapid X2 was a more powerful version of the Rapid X that I tested previously, taking advantage of improvements in battery and LED technology to kick out more light than the original – a claimed 50 lumens. What Cateye appears to have done here for the new X3 model is simply stick two X2 lights together side by side, in a single package.

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There are two separate LED strip lights now, and maximum output is lifted to a stonking 100 lumens. Unusually, the two strip lights are operated independently, each with its own button to select from the six available modes, giving a possible 48 different combinations (go on, maths pedants: I dare you).

Unlike some other premium rear lights, which use reflectors or collimated lenses to direct their light in a beam for maximum range, the Rapid X3 is a spread-it-around sort of light. As a consequence, you can mount it at any angle and it's highly visible, even from a side angle of more than 90 degrees. Using it, I felt pretty confident that other road users could see me from any direction, even in poor conditions.

The Rapid X3 is chunkier and weightier than the previous versions, obviously requiring more battery capacity to kick out that much light. It still sits neatly behind a seatpost, though, held in place with one of four rubber o-rings. It's a simple system but one that works well. It'll fix to a seatstay or rack tube too, using the smallest of the o-rings, and there's also an extra rubber skirt designed specifically for use on an aero seatpost. That's a nice touch as aero road bikes are becoming more popular and some lights simply won't fit their seatposts.

Cateye offers an optional Spacer X clip that allows you to attach the light to even more things, such as a bracket on a rack, a Fizik saddle clip or one of Cateye's FlexTight brackets. I didn't really see the need for this but others might.

Being able to choose a mode for each side allows you to combine two different outputs from a single light, to eye-catching effect. There are two constant settings, with the high mode giving 50 lumens per side versus 10 lumens for the low mode. If you set both sides on high then burn time is a measly one hour, so you'll only want to use that on short rides. That compares poorly to the likes of the Knog Blinder R70 (review coming soon) and Bontrager Flare R (review also coming soon, but for now you can read about it here), both very bright lights that can manage over three hours on constant full-power mode.

Cateye quotes battery life for each of the modes, assuming that both sides are using the same setting (see test report, below). The 30-lumen flash mode is good for 30 hours, and would presumably do twice that if you only used one side. Using only one side isn't a great idea, though, as it means that lateral visibility from the other side is greatly reduced. Using the lower constant setting on one side with a flashing mode on the other was my preferred option and gave enough juice for a week's commuting, which is my basic requirement of a rear light.

There are flashing modes of varying frequency and intensity, plus a pleasing pulse mode which is a bit gentler on the eyes – good for when you're riding with mates.

Operation is pretty simple: push and hold a button to switch that side on or off, and push it again to scroll through the modes. It's easy to operate both buttons together using one hand. Mode memory is always welcome on a light, especially with so many possible settings here. Switch it off, and it'll come back on next time with the same mode(s) that you were using previously.

> Check out our guide to the best rear lights here

The X3 has a lithium-ion battery which is USB rechargeable, via the ubiquitous micro-USB socket now located at one end. This sits under a rubber flap that seems to do a good job of keeping water out. I've used it in some pretty nasty weather with no problems.

When the battery is getting low, the light will switch to the flash mode to eke out what charge there is remaining, and one of the buttons will flash red. It'll still last for a good few hours in this state, so you should have plenty of time to reach a charger without being left in the dark.

I've used various models from Cateye's front and rear light range extensively over the years, and have had very few problems with them. This light gives you a lot of confidence that you'll be seen by other road users behind and to the side of you, and is among the very best rear lights I've used. At £55 it's not cheap for a rear light – you can get a decent rechargeable light for £20 nowadays – but in its price bracket this would be my first choice.


Fantastic all-round visibility from a neat package, though you won't get 100 lumens for long

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Make and model: Cateye Rapid X3 rear light

Size tested: 100 lumen

Tell us what the product is for, and who it's aimed at. What do the manufacturers say about it? How does that compare to your own feelings about it?

The ultimate safety light.

The Rapid X3 represents the pinnacle of safety light technology, designed to ensure you're seen both day and night. Doubling the brightness of our popular X2, the X3 100 lumens in the rear. Featuring our most versatile system, the Rapid X3 easily mounts to almost any application, including round and aero seatposts, seatstays, handlebars, forks and headtubes. With the optional Spacer X accessory, the X3 fits our FlexTightTM, rear rack, saddle rail and Fizik saddle brackets too. Add the best side visibility in it's class, and you have the ultimate safety light.

Tell us some more about the technical aspects of the product?

Dimension: 74.0 x 31.0 x 39.0 mm

Weight: 46g (with batteries)

Light source: COB LED

Battery: Lithium-ion rechargeable battery


High mode (100 lumens): 1 hr

Low mode (20 lumens): 5 hrs

Flashing mode (30 lumens): 30 hrs

Rapid mode (50 lumens): 16 hrs

Pulse mode (20 lumens) :16 hrs

Vibration mode (30 lumens): 8 hrs


Recharge time: 3 hrs (USB2.0)

Mount size: Rubber band mount (fits f 12.0-32.0mm)

Other : Battery auto save, Low battery indicator, Light mode memory

Rate the product for quality of construction:

Other lights in this price band arguably feel more premium, thanks to the use of aluminium instead of plastic. However, there's not much wrong with how this is put together and I'd argue that performance is what you're really paying for.

Rate the product for performance:

Superb visibility from just about any direction. Battery life is good on the flashing modes but an hour is pretty unimpressive on full power constant compared to the competition.

Rate the product for durability:

I've had no issues with the old Rapid X that I reviewed (and have continued to use regularly since) and I can't see any obvious weak points here.

Rate the product for weight (if applicable)

Other less bright lights may weigh less, but I don't think that the weight of this is likely to be an issue for many people.

Rate the product for value:

You can get a perfectly adequate rechargeable rear light for £20 so it would be hard to give this top marks. You do get twice the output that last year's X2 managed for only a third more money, though.

Tell us how the product performed overall when used for its designed purpose

Very well – it is my current favourite rear light.

Tell us what you particularly liked about the product

All-round visibility, neat package that's easy to swap between bikes, and a wide range of modes.

Tell us what you particularly disliked about the product

It would be nice to see a longer run time on the headline 100 lumen setting.

Did you enjoy using the product? Yes

Would you consider buying the product? Yes

Would you recommend the product to a friend? Yes

Use this box to explain your score

I reckon this is probably my favourite rear light on the market at the moment. It might not have the focused range of the likes of the Bontrager Flare or the Knog Blinder R70, but it more than makes up for it with better side visibility than either. Loses a star because of the 1 hour run time on max power, which is well down on either of these competitors.

Overall rating: 8/10

About the tester

Age: 37  Height: 190cm  Weight: 78kg

I usually ride: Commuter - something with disc brakes, drop bars and a rack  My best bike is: Rose X-Lite CRS

I've been riding for: Over 20 years  I ride: Most days  I would class myself as: Expert

I regularly do the following types of riding: road racing, time trialling, cyclo-cross, commuting, touring, club rides, sportives, general fitness riding, fixed/singlespeed, mountain biking

Jez spends his days making robots that drive cars but is happiest when on two wheels.  His roots are in mountain biking but he spends more time nowadays on the road, occasionally racing but more often just riding. 

Add new comment


omar | 2 posts | 6 years ago

Hi Jez Ash,

Another question  1 Say I am buying this to use only in flash mode, do you still think it is worth buying or other lights will perform as good?

Thanks for the feedback!! omar

Jez Ash | 276 posts | 6 years ago


I can't measure the lumens, so I'd go with what the numbers say.  On flash mode, it's not as bright as on high mode.

I've used the test unit for about a year, commuting in all weathers, and it's survived the rain just fine.  Getting the rubber bung on the end to fit in properly is a bit fiddly, but mine has coped ok with UK rain (which isn't like Singapore rain!)  It sounds like others haven't been as lucky.

omar | 2 posts | 6 years ago


Pardon my ignorance, I have some questions on this light and its brightness.

High mode       (100 lumens):  1 hr  
Low mode            (20 lumens):  5 hrs
Flashing mode     (30 lumens):30 hrs 
Rapid mode         (50 lumens):16 hrs 
Pulse mode          (20 lumens):16 hrs 
Vibration mode   (30 lumens):  8 hrs

Based on the above info, I realised the light is only on its brightest 100lumens in 'high mode'

1) I wish to know if it is still the brightest light if I put it on 'Flashing mode' which is 30lumens?

2) How is the waterproofing? Being in Singapore, some of my best lights failed after riding once in heavy rain.

I am this close to purchasing one  1 Any comments appreciated. /omar

benjiweber | 1 post | 7 years ago

I've been through two of these. It's beautifully bright and has great all-round visibility.

Unfortunately a bit of rain kills them rapidly. The seal is terrible, a bit of road spray and water gets into the electronics and it won't turn on any more.

The seatpost mounting only exacerbates the situating, ensuring it gets a good soaking if you don't have mudguards.

I've swapped for a less bright lezene light that has a decent seal.

harrybav replied to benjiweber | 625 posts | 7 years ago
article wrote:

48 different combinations (go on, maths pedants: I dare you)

It's actually only 27 combinations. Order is unimportant in combinations. But there are 48 permutations.

shmooster replied to benjiweber | 28 posts | 7 years ago
benjiweber wrote:

I've been through two of these. It's beautifully bright and has great all-round visibility. Unfortunately a bit of rain kills them rapidly. The seal is terrible, a bit of road spray and water gets into the electronics and it won't turn on any more. The seatpost mounting only exacerbates the situating, ensuring it gets a good soaking if you don't have mudguards. I've swapped for a less bright lezene light that has a decent seal.


Same issue for me, there seem to be two designs, one with the charging port on the end which doesn't seal well, and one with the port on the back like the earlier Rapid X models. Mine had the port on the end of the light, failed after one ride in the rain, and apparently not covered under warranty. One to avoid sadly.

Anthony.C | 274 posts | 7 years ago

Unfortunately the Cateye Fizik saddle bracket doesn't seem to be available over here.

userfriendly | 620 posts | 7 years ago

I've got one, love how it mounts flush to the seatstay - looks excellent. And leaves the seatpost for the Fly6. Ridiculously bright. And agreed, one side on low constant and the other one flashing is my preferred setting as well. Brilliant little thing.

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