Nearly great rear LED, weather sealing let our test model down
RSP Astrum LED rear light
7 10

RSP’s Astrum is a really funky design with retina burning output, frugal battery consumption in flashing modes, a positive switch that doesn’t accidentally engage in the bottom of a bag yet easily operated in full-length winter weight gloves. Even the rubberised seat post bracket seems better than most. However, disappointing eighteen and three-quarter hour run-times (twenty hours quoted) in static mode and suspect sealing blotted its copybook.

Measuring a bijous 67x27mm the Astrum incorporates two extremely bright bulbs that Raleigh assert are visible from up to a kilometre away-a claim I certainly believe and given their intensity, position lower on clothing, bags or most obviously the bike so as not to dazzle traffic approaching from behind. On paper, three modes (two flashing and one static) sounds unimpressive but their quality more than compensates for top-trumps quantity-especially sideways visibility. That said vertical mounting has the edge-especially tackling roundabouts and emerging from junctions.

Build quality seems generally pleasing right down to the crude yet competent mounting bracket. Thoughtfully this features an integral Phillips screw so as to fine tune the angle of beam and it affords a good fit on most seatpost diameters. However, experience suggests, it’s of the sort that becomes brittle over time. The clothing clip offers good purchase on most materials from jersey pockets through to messenger bags with no apparent lemming tendencies over rougher lanes.

Run times are literally a tale of two cities- seventy- seven hours in flashing modes using the original AA batteries compared with eighteen and three quarters in static (quoted 80 and 20 hours respectively). That said, battery exchanges are easily performed using a coin to prise open the back but the seals on our test model weren’t up to scratch, allowing water to penetrate on long, wet rides sans guards. Running Vaseline around them has greatly improved matters, although telltale condensation is still apparent following really, really wet outings.


Potentially one of the best LEDs on the market let down by so-so weather seals

road.cc test report

Make and model: RSP Astrum LED rear light

Size tested: n/a

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?

"2 1/2 watt LED's, fully waterproof construction, with flashing and constant modes make this one of the highest performance rear LED's on the market.

2 x 1/2 watt output. Visible up to 1000m. Burn time up to 80 hours.

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

2 x 1/2 watt output. Visible up to 1000m. Burn time up to 80 hours. Powered by 2 AA batteries quoted run times 20 (static) up to 80 flashing. Actual run times 18.45 hours and 77 respectively.

Rate the product for quality of construction:

Generally good but poor seals.

Rate the product for performance:

Really, really bright with fantastic run time in flashing modes but battery consumption is frightening in static mode.

Rate the product for durability:
Rate the product for weight, if applicable:

86g (including bracket & batteries).

Rate the product for comfort, if applicable:

Lovely to use with a really well designed switch.

Rate the product for value:

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

The output in both static and flashing modes is fantastic and I can well believe it's visible from 1km. A really positive switch is simple to use in full-finger, winter weight gloves and more importantly won't accidentally switch on in the bottom of a bag. Batteries are easily replaced by the roadside and the bracket might look a little chunky yet enjoys surprising adjustability. However, it's thirsty in static modes and the weather seals on our test model were disappointing.

Tell us what you particularly liked about the product

Great output & nice detailing

Tell us what you particularly disliked about the product

Poor static run time and disappointing weather seals.

Did you enjoy using the product? Yes

Would you consider buying the product? Yes, with improved seals

Would you recommend the product to a friend? Yes (seals allowing)

Overall rating: 7/10

About the tester

Age: 36  Height: 1m 81  Weight: 70 kilos

I usually ride: Rough Stuff Tourer Based around 4130 Univega mtb Frameset  My best bike is: 1955 Holdsworth Road Path and several others including cross & traditional road

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

I regularly do the following types of riding: cyclo cross, commuting, touring, fixed/singlespeed, mtb,

Shaun Audane is a freelance writer/product tester with over twenty-eight years riding experience, the last twelve (120,000 miles) spent putting bikes and kit through their paces for a variety of publications. Previous generations of his family worked at manufacturing's sharp end, thus Shaun can weld, has a sound understanding of frame building practice and a preference for steel or titanium framesets.
Citing Richard Ballantine and an Au pair as his earliest cycling influences, he is presently writing a cycling book with particular focus upon women, families and disabled audiences (Having been a registered care manager and coached children at Herne Hill Velodrome in earlier careers)


el.dudino [73 posts] 7 years ago

Shame the seal isn't great, I'd been looking at one of these to supplement my Nite Rider Cherry Bomb for the winter.

paulfrank [93 posts] 6 years ago

Mine has been brilliant after sealing with some baseline but if you are running lots of miles on rough roads like the potholed nightmares around Telford you might find it self destructing like mine leaving the clip firmly clamped in the bracket but missing the light itself. Hopefully RSP will do a Mk.II with a strong case for those cracking LEDs.

mrdgreene [3 posts] 5 years ago

The bracket on my Radient (similar model but with USB charging) has just snapped due to rough roads. Clip left attached to bracket as per @paulfrank post.
A shame as its a great light otherwise.

sfichele [140 posts] 3 years ago

I've had a few of these, and for the money they are a great light. However, they dont play nice with potholes, I've had two self-destruct on me after hitting a bump. The back falls out and then scatters over the road spilling your batteries. I've had to tape them together to stop them doing that.

drag2xs [1 post] 3 years ago

Got my first light 2 years ago and have just had to replace with No. 5. I do love this light especially when it's dark enough I can look in my mirror and see road signs far behind lit up in red reflection! The first 2 broke off and although I retraced for miles I never found them; the third I heard fall off and saved it as a working light needing a new means of attachment and the fourth broke last Sunday but I'd tied a plastic coated thin garden wire around the middle which was then looped over the tensioning nut (very quick to remove and put back on) so all that happened was that it dangled slightly lower down and I was able to secure the light to the seatpost using that wire which had been on since No. 3 broke so I've now got that light and it's rechargeable batteries which are now in No. 5.
Does anyone know if the newer USB version has a modified attachment clip? as I now need another spare for WHEN this one breaks off. There are various other 1W rear lights that I might have to try as these continue to fall off.
The offending clip can be removed via 3 very small screws but I'm sure that replacements aren't produced but I'd love one in metal! - or made on a 3D printer.

timtak [66 posts] 9 months ago

I bought one about 6 years ago in Melbourne Australia and it has outlasted about 10 chinese rear lights. The clamp went but the waterproofing was (though insufficience for British weather perhaps) superior to its East Asian competitors, some of which looked similar. The button is better and easier to use even in thick cloves. After the clamp died I bolted the base to my rear panier with a countersuck headed bolt. The light has at last given up the ghost at least on one side, due to water damage. I was thinking of trying to persuade a British supplier to send me one here to Japan from the UK but I note that it is over ten times the price of cheap Chinese ones even without shipping costs so I think I will continue to use Chinese lights adding (suggested here) vaseline and perhaps silicone sealant. I am missing this light though. The seal is not great, but it is better than many.