Topeak's Redlite Aero USB rear light is a simple yet surprisingly capable two-mode LED that delivers decent output and good run-times between charges. Ours returned over 10 hours on constant and nearly 40 on flashing from a full mains charge. That said, there's also an AAA battery sibling for those preferring not to be tied to PCs or similar power sources.
The Redlite has several mounting options, with round, aero and bag adaptors. In practice I've had no problems persuading the aero bracket to play nicely with round as well as aero seatposts or, at the other extreme, pencil thin seatstay tubing.
Rubber feet hug the surface, ensuring that the light stays flat, while a choice of three rubber bands wrap around the light body's lugs and your tubing.
While the aerodynamic advantage is little more than slick marketing, the slender profile has helped, especially when mounted low on the seatstays – I've never clouted it when mounting or dismounting cyclo-cross fashion.
Looking through the injection-moulded plastic lens and housing reveals three LEDs, which are carefully angled to project them in a straight line, irrespective of position. The dome shaped lens offers excellent peripheral bleed and a 220-degree arc of light.
The switchgear is located at the top, the USB port beneath. I've spared ours the hosepipe treatment but even when positioned just inches from terra firma and blasted with all sorts of dodgy wet stuff, it's never missed a beat.
At the opposite end lives a simple, rubberised switch that's easily operated in gloved hands and made even simpler by only having the two settings: steady or flashing.
While it's not the brightest light out there, steady is still bold enough to be spotted from 250m along unlit B roads, and the deep red glow seems more effective than some boasting 60 lumens or more on gloomy winter afternoons.
Flashing has been my default for the most part, primarily because it has more punch and uses less juice. Again, we're talking a very reasonable 300m in the sticks, dipping to half that through city limits. Experimenting with the straps enabled it to be mounted atop some helmets, which also improved visibility – friends reckoned 325m and 180 for flashing/steady respectively.
Ultimately, it's not the most potent light, and on paper looks like it would struggle to compete with more powerful and often cheaper models, but run-times and its actual presence more than compensate. So long as the battery is carefully charged before being placed into hibernation, it should enjoy a long and useful life.
Simple but very effective rear light with decent build quality
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road.cc test report
Make and model: Topeak Redlite Aero USB
Size tested: 6.6x2.4x3.4cm
Tell us what the light 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?
Topeak says: "Slim, aerodynamic tail light fits aero / round seatposts, seatstays or Topeak bags perfectly. Rubber strap allows tool-free mounting / removal and multi mounting positions".
Certainly sleek and surprisingly effective but suggestions of aerodynamic advantage should be taken with a large pinch of salt.
Tell us some more about the technical aspects of the light?
3 super bright red LEDs
3.7 V 220 mAh Lithium Ion (integrated)
Constant / Blinking
Burn Time (approx)
10.5 hr Constant /
40 hr Blinking
Reserve Time (approx)
Charge Time (approx)
Injection molded plastic
Seatpost / Seatstay / Topeak bags
Low battery indicator
Size (L x W x H)
6.6 x 2.4 x 3.4 cm /
2.6' x 0.9' x 1.3' (Light)
22.2 g / 0.78 oz (Light)
Decent quality materials and well sealed in the everyday sense.
Simple two-mode design with user-friendly switch.
Good quality and effective but seems a little costly for only two modes.
Tell us how the light performed overall when used for its designed purpose
Overall, I've been impressed by the Redlite Aero USB. It's a surprisingly effective two-mode light. Two modes might sound low rent by contemporary standards but the surface area and light quality is very distinctive. Run-times are extremely generous - good enough for hardcore night owls and forgetful commuters alike.
Tell us what you particularly liked about the light
Good quality, clever, yet user-friendly design.
Tell us what you particularly disliked about the light
While not outlandish, the lion's share of £30 feels quite expensive for a two-mode model.
Did you enjoy using the light? Yes
Would you consider buying the light? It has proved a pleasant surprise, so possibly.
Would you recommend the light to a friend? Yes
About the tester
I usually ride: Rough stuff tourer based around 4130 Univega mountain bike 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, mountain biking
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)