Here’s a nice review of Bontrager’s Flare R from VeloNews
Weight: 35 grams
We like: Crazy bright for day or night use, easy mount bracket
We don’t like: Weatherproofing in cold temperatures is not up to par
The Bontrager Flare R, a massively bright rear light, can dazzle even at high noon, with a purported daytime visibility of two kilometers and eye-catching blink patterns. It might not survive a snowstorm, though.
The sense of security that the Flare R provides, even in the middle of the day, is fantastic. It is truly the brightest rear light that VeloNews has ever tested, so bright that your riding partners might ask you to turn it off during pace line riding, even in the middle of the day. 270-degree visibility means that cars can see you coming from side streets. Bontrager is pushing the Flare R as a light to be used any time you ride, day or night, and we love that idea almost as much as we love not getting hit by cars.
On full beam, a full charge lasts just over four hours, or just under six hours on daytime blink mode. Nighttime blink mode provides almost a full day of run time — 23 hours. That’s impressive for a 35-gram unit that charges in about 2.5 hours with a micro-USB cable. A single, large button on the top turns the light on and off and cycles between modes.
The Flare R comes with two mount brackets, one stretchy rubber contraption that easily mounts to most seatposts (long, aero seatposts might be an issue) and another clip to attach the light to clothing. Both are solid and dependable.
Now, the downside. We killed two Flare R units in very cold, very wet conditions. Summer rainstorms were never a problem — perhaps the rubber sealing is more effective when it’s warm and supple. Both Flare Rs died after the same cold, wet ride in an incoming snowstorm, as temperatures dropped to around 30 and heavy spray from the rear tire shot up at the rubber-covered USB port.
Prior to this one (rather large) issue, the Flare R performed admirably for more than six months, and two other units in for testing are still going strong. Few lights can get a driver’s attention in the middle of the day like the Flare R.
Read more at http://velonews.competitor.com/2015/11/bikes-and-tech/reviewed-bontrager-flare-r_389946#zuc9O0Ef0aWEE5e7.99