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Verdict: 
Small but very mighty pairing with brilliant daylight modes
Weight: 
60g

The Bontrager Ion 100 R/Flare R City Bike Light Set are a very small, yet surprisingly mighty pairing. Boasting 100 and 35 lumens (front and rear respectively), clever optics ensure they've enough punch on their own for town. Or, they could be used as backup lights to more powerful systems on more clutter-phobic best bikes.

Pros: Small, optical sensors optimise output and run times. Particularly suited to clutter-phobic best bikes

Cons: Pricey (at full RRP) compared with other pairings boasting similar outputs.

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Up front, the R100, no-one will be surprised to learn, uses a single Cree LED. What is special is the light's sensor, which automatically reads and tailors output to suit surroundings. Crudely, this works to the same principle as reactive sunglasses. This means both lights boost their output during daylight, regardless of whether they're in steady, or flashing modes.

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Output also automatically kicks down when their lithium ion reserves tumble to 5%. Both units use a lens and reflector designed to cast a wide beacon of light, which is ideally suited to urban/built up contexts but translates equally well to rural and open roads.

Modes

Both lights have four settings. Day steady, day flashing and night steady/flashing. Like most contemporary designs, there's a memory function, defaulting to your last selection for convenience.

However, while small, the switches are easily operated in all but the most densely padded, winter gloves. The battery life indicator is thoughtfully positioned alongside, for easy monitoring.

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Weather Resistance

Both lights meet the IPX46 standard for water resistance, which on paper means heavy rain. I've had no problems with either, the rear mounted low on the seat stays. Aside from waterlogged lanes, I've left them in situ when giving bikes sudsy bucket washes and treated them to point blank blasts from my garden hose. Neither missed a beat and no moisture snuck behind the micro USB port flap, which is similarly snug fitting.

Charging

Mains charging is my default choice and will take two hours to charge these two. Bargain on another twenty minutes if they're feeding from a laptop, or similar portable tech. It'll emit a subtle red pulsing light during the charging phase. Some higher current cables sliced ten minutes or so from the cited times but any generic micro usb offering, will do the job just fine.

Mounts

These follow the neat, tidy and easy to live with narrative. Both will accommodate most common post and bar diameters. Yes, right down to 22.2 bars and, including 'aero' patterns, although admittedly, they're a slightly flusher fit to round bars/posts. I've mounted ours around 1/18th head tubes, without any problems.

The lights detach in the same fashion, as a flashgun from a camera hot-shoe. Convenient when you want to recharge them but to be honest, I've whipped both off when parking in the street. It's worth giving them a good warm water flush through from time to time. Especially if they're serving on 'cross and gravel type builds without mudguards.

Performance

According to Bontrager's blurb, these are visible to 500 and 400 metres respectively. I've not been able to measure this in a controlled, scientific sense. However, they do pack a surprisingly mighty punch-day or night.

The clever little sensor component genuinely seems to offer an advantage over other blinkies boasting similar output. Flashing has been my default setting for both and I've been pleasantly surprised by how effective the distinctive phasing is at nailing driver attention.

Even on a really bright day, the wide angled beam has been distinctive enough that drivers slowed, or at least thought twice before sweeping out from a junction.

Friends on two wheels and four, reckoned they could pick out the light at 125 metres during the day. Steady is reckoned 60, maybe 70 metres.

At night and through built up areas its closer to 200 metres and 125, given the competing illumination. On open roads and fairly clear skies, feedback from other riders suggested I was conspicuous at 300 metres in flashing, 125 steady.

Out in the proper dark I was running a main 800 lumen Exposure Revo Mk1 dynamo, or similarly potent main light but the moving light and bluish hint caught and held the attention of other traffic; pedestrians too.

As expected the level of attention they command was particularly helpful when filtering through lines of slow moving and stationary traffic. In the highest, steady setting, there is enough bite for it to stand alone, as a town light - which of course is what this combo is designed for.

Mind you, I still felt a little vulnerable, using it as my only source of lighting and it emits a very subtle, bluish tint reminiscent of 'white' LEDs found on torch-type commuter lights 20 years back.

That said; racing dusk back home and along less trafficked roads, the perky little light is suitably effective, intensifying output when facing a more powerful vehicle headlamp.

In the steady mode, there's just enough navigational punch to limp home, along the backroads, in the event of main system shut down (say, shorted dynamo wire). We're talking 12mph tops but I've had no problems being seen by other road users.

Repeated loops of urban and rural nature suggests the sensor is very discerning and not easily confused by competing light sources. Run times have been faithful (virtually to the minute) to those cited by Bontrager.

Rear light

I reviewed the Flare R City rear light last autumn - so if you want more detail on it you can read the standalone review of the Flare R here. In short though it's similarly capable to the Ion 100 R and because of the sensor technology in particular, a good deal brighter than you might expect a 35 lumen light to be.

Since we're on the subject, there will be many, myself included who regard 30 odd lumens slightly overpowered (though not anti-social) in suburban contexts and potent enough for open roads, save for the darkest lanes, fog etc.

Like its front sibling, the curved back and silicone mount directs the light at 16 degrees. Aside from the obvious difference in output, the intelligent sensor optimises output and therefore, run times.

Night flashing is quoted as returning 15hrs 56 (16 quoted but quibbling this would be churlish) eight in daylight, whereas in daylight steady mode this plummets to a slightly disappointing 3 hours. The thriftier settings though should suit most riders, even those, like yours truly, who love dusk till dawn all-nighters.

One thing I have noticed, with both lamps get surprisingly warm, given a few hours. Part of this is attributable to their rubberised housing.

We're not talking singed digits by any means and to date, it doesn't seem to affect performance. On clear night and open roads, other riders reckon they spotted me at 220 metres, in the night flashing mode.

This dips a bit, when things turn cloudy. Round town, this seems around 110 but the beam pattern and intensity is still very distinctive.

In daylight flash, I reckon 400metres isn't an overstatement and those intelligent optics ensure it doesn't become overly harsh at close quarters. That said; I've slipped ours into day steady, to placate some riding companions.

The bail out/limp home 2 lumen mode is also brighter than I would expect and a whole heap better than being plunged into darkness. 30-40 metres seems to be the general anecdotal consensus. Nonetheless, I'd be wanting to avoid this scenario wherever possible.

Peripheral prowess is impressive, thanks to the lens and other optical features. To my surprise, I could certainly get away with it as a single rear light, especially on a pared to the essentials TT type build.

However, for really dark roads, I still favour rear lights with larger surface areas like the Cat-Eye rapid X rear light or the Infini Sword super bright 30 COB rear light

Conclusion

The technical sophistication of the R100 front and the Flare rear light makes them a very capable, minimalist pairing well suited to scooting round town and their daylight modes are particularly impressive.

However, if you don't feel you need all that technical innovation and optical precision there are several other lights which are slightly larger but a fair bit cheaper than the R100/Flare R combo at full RRP that still offer an excellent balance of output and economy… however (and you probably guessed that second 'however' was coming) if you're buying online at the time of writing this review I struggled to find anywhere online that wasn't selling this lightset at £20 off full RRP either and I'd guess the same would apply to many local bike shops too.

Verdict

Small but very mighty pairing with brilliant daylight modes

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road.cc test report

Make and model: Bontrager Ion 100 R/Flare R City Bike Light Set

Size tested: Includes Ion 100R, Flare R City, two quick-connect brackets and a micro USB charging cable

Tell us what the light set is for

Bontrager says 'One light set for a complete daytime running lights solution. The Ion 100 R and Flare R City feature focused optics, an interruptive flash pattern and a broad range to ensure visibility. Their compact design and wide beam spread are optimised for city riding and make these USB rechargeable lights great for any bike'. My feelings "Broadly agree, although would want something better sealed as (a secondary system) for mountain biking".

Tell us some more about the technical aspects of the light set?

"* Be seen with a broad, powerful beam and balanced optics designed for city riding

* Includes Ion 100R, Flare R City, two quick-connect brackets and a micro USB charging cable

* Bontrager Daytime Running Lights feature the flash, focus and range to be seen during the day

* USB rechargeable

Creating a light visible in the daylight requires intentional design. By directing or amplifying output, we intensify the beam or extend its range. Without this, a light may appear bright, but will not be noticed in the day.

Flash

Most rear lights use a steady flashing pattern. This pulsing is less noticeable than one that continually varies its intensity and pattern. The Day Flash setting featured on Bontrager Daytime Running Lights was created to specifically increase noticeability with varying outputs and an interruptive flash pattern.

Range

Daytime Running Lights are brighter than what you would use at night in order to give drivers more reaction time. Bontrager Daytime Running Lights are detectable from a greater distance than other lights, from � mile to over 2km away in daylight conditions given the specific model".

Rate the front light for quality of construction:
 
8/10
Rate the rear light for quality of construction:
 
8/10

Seem well made and ultimately, well sealed from the elements. No less than I'd expect from Bontrager, or this price point, though.

Rate the light set for design and ease of use. How simple were the lights to use?
 
8/10

Intuitive and very user-friendly, despite their diminutive size.

Rate the front light for the design and usability of the clamping system
 
8/10
Rate the rear light for the design and usability of the clamping system
 
8/10

Stretchy rubber strap entertains most diameters of tubing, from oversized bars and seat posts, to head tubes and seat stays.

Rate the front light for waterproofing. How did it stand up to the elements?
 
7/10
Rate the front light for waterproofing. How did it stand up to the elements?
 
7/10

IPX 46 means heavy rain. There's been no problem in that context, or when subjecting them to my hosepipe test.

Rate the front light for battery life. How long did it last? How long did it take to recharge?
 
7/10
Rate the rear light for battery life. How long did it last? How long did it take to recharge?
 
7/10

Very faithful to those cited- at the mains.

Rate the front light for performance:
 
8/10
Rate the rear light for performance:
 
8/10

Remarkable for their size, thanks to the sophisticated optics and sensors. That said; I'd probably opt for, or pair the rear with something like Infini Sword. If my rides involved long, steady miles along unlit, open roads.

Rate the front light for durability:
 
8/10
Rate the rear light for durability:
 
8/10

See no obvious problems to date.

Rate the front light for weight:
 
9/10
Rate the rear light for weight:
 
9/10
Rate the light set for value:
 
7/10

Good overall, especially given the output and technology involved - and especially if you shop around as this set can be found for a good bit less then full price

Tell us how the lights performed overall when used for their designed purpose

Overall, the Bontrager Ion 100/R flare city bike light set are a small but mighty pairing, perfect for clutter-phobic bikes, where its a question of being seen. High quality optics and sophisticated sensors mean the light is automatically tailored to suit conditions and the daylight modes are particularly impressive in that respect.

Tell us what you particularly liked about the lights

Size, output and self-adjusting sensors.

Tell us what you particularly disliked about the lights

Nothing, given their design brief

Did you enjoy using the lights? Yes

Would you consider buying the lights? Yes

Would you recommend the lights to a friend? Yes

Use this box to explain your overall score

Very capable lights for town work, or clutter-phobic bikes. Easy to use and reasonably priced, when everything's taken into account. That said; the rear wouldn't replace something with a larger surface area, if a lot of time is spent riding unlit roads.

Overall rating: 8/10

About the tester

Age: 44  Height: 1m 81cm  Weight: 70kg

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)