With advancements in technology and batteries, bike lights have transformed from being low powered and bulky to lightweight and compact units. The Bontrager Ion RT and Flare RT light set are a great example of this transformation. With diminutive sizes, the Ion RT headlight and Flare RT taillight offer daytime visibility with decent run-time and USB rechargeable batteries. Aside from the standard multiple output modes, the lights also boast Bluetooth connectivity to compatible Bontrager and Garmin computers allowing you to remotely control the lights.

The Bontrager Ion RT and Flare RT are compact and high tech lights that pack a punch. Particularly when paired with a compatible bike computer, the lights can function nearly automatically based on speed and light conditions.

To allow for daytime visibility both the headlight and taillight have a ‘day flash’ output mode that uses maximum lumen output. The headlight has an impressive 200 lumen max output mode while the taillight has a 90 lumen output. In this review we’ll be looking at the light set which has a retail price of $114.99 which is a slight discount over the individual prices of $59.99. Both lights are lightweight and use simple rubber straps to attach to the bike without the need for tools. 

CategoryBicycle Head + Tail Light
Rating 8.4/10
Retail Price $114.99 ($59.99 individually)
Measured Weight (in g) 34/32 (headlight/taillight with mount)
Likes+ Compact form factor
+ Daytime visibility without weight penalty
+ Connects to compatible computers
Dislikes– Premium price
– Confusing number of output modes
– Aero mount / body clip not included
Where to Buy (US)Trek Bikes


Bontrager packages the two lights together in a simple cardboard box with bright graphics. Unlike other products we’ve reviewed, the lights aren’t visible through the packaging. Inside the box there is a tidy plastic tray that holds the lights and mounts in place.

In the box you’ll find:

  • Ion RT headlight
  • Flare RT taillight
  • 0° offset handlebar mount
  • 16° offset seatpost mount
  • Micro USB charging cable
  • User manual

Note, we highly recommend taking a look at the user manual for these lights as they have a number of features that aren’t typically found on bike lights.


Both the headlight and taillight use a similar plastic mount with rubber straps to secure them to the bike. The rubber straps feel thick and sturdy with multiple attachment points to accommodate different diameters. To account for the seat post angle, the taillight mount has a built-in 16° offset. Interestingly the lights can also be rotated around the mounts a full 360°. Although we aren’t sure why this feature was added (note the light output would be the same regardless of rotation with the lens design), it feels secure and doesn’t add any jitter. Bontrager unfortunately doesn’t include a body clip for the taillight to allow for backpack or saddlebag mounting. However, they do sell the body clip and a variety of other optional mounts such as aero posts or Blendr accessories.

Bontrager Ion and Flare RT - straps
Lights use simple rubber straps
Bontrager Ion RT mount
Slot style mount is secure and simple to use


What really impressed us with the Bontrager lights is the compact and modern form factor. Both lights use the same plastic housing and mount attachment design. Visually, the only difference between the two lights are the model names printed on the top and the red tint on the taillight inner lens. The lights are nearly square with the lens centered on the front face. According to Bontrager, the lights are also 36% lighter while boasting 40% more lumens. Visually, they don’t look much different than a set of dice and with the black housing blend in with your bike when turned off.

At first glance we were concerned about the lack of side visibility with the lights, however the housings have built in transparent windows on each side which allow for some light to be visible from the side angle. Although the side visibility isn’t as great as other lights we’ve tested (i.e. Topeak Redlite or Planet Bike Rojo), it helps improve safety and visibility. There is a large power button on the top of the lights that is easy to use, even with gloves on. Next to the power button are the LED indicator lights. Blue indicates the wireless connectivity is active, green indicates good battery life while red is low battery status (blinking red if the battery is very low). These status indicators are easy to see and intuitive, however we would have preferred a battery indicator design more similar to the Fenix BC05R taillight. The USB port is located on the bottom of the light with a cover that has been improved in this latest version.

Bontrager Ion RT - side profile
Transparent housing helps improve side visibility

In terms of usability, the lights use a standard one button interface with some additional unique features. A long hold turns the light on and off, while the single press cycles through the available modes. What is interesting here is that Bontrager has incorporated some additional features that can be activated by doing a long hold. There is a mode lock feature that prevents the light from being switched out of the selected mode. This is a feature we haven’t seen before (it’s more common to see a “transport mode” that prevents the light from being turned on when in a backpack or pocket) and we suspect most people won’t know the feature exists. 

Bontrager Ion RT
The 200 lumen headlight works great for daytime visibility

The lights also feature an ambient light sensor, which is disabled from the factory, that can switch the light between day and night modes. To toggle the feature on or off, you simply have to hold the power button with the light off and release the power button after the light flashes. With the feature enabled, the lights will switch between daytime to nighttime modes automatically. The Ion 200 headlight will switch between daytime flash to steady high mode while the Flare RT taillight switches between day flash / all day flash to night flash or day steady to night steady. Personally we really like this feature as it automatically adjusts the mode to the current light conditions.


Another innovative feature with the Bontrager lights is the fact that they have built in ANT+/Bluetooth connectivity to compatible Garmin and Bontrager computers. Depending on the computer, this means you can automatically turn the light on or off based on speed, monitor battery status, and even switch between day/night modes. We tested this with the Bontrager RIDETime Elite computer which didn’t show battery status (only a low battery warning) and found the pairing process to be painless. Particularly with the auto on/off feature (over 3 mph it turns on, and shuts off after 3 minutes of no motion) you never have to touch the power buttons of the lights (simply start riding). We found this to be a very similar experience to theLight and Motion Vya Pro headlight (and the other Vya smart products) which utilize built motion sensors.


Each of the lights features five unique output modes with non-adjustable power levels. The Ion 200 RT headlight has: high (200 lumens, 1.5 hr), medium (100 lumens, 3 hours), low (5 lumens, 14.5 hr), night flash (5 lumens, 30 hr) and finally day flash (100 lumens, 12 hr). Although Bontrager claims the headlight can be used for both ‘be seen’ and ‘to be seen’ we found that even the high 200 lumen steady mode didn’t have enough output to confidently ride on dark trails. We would give the headlight a similar assessment to the Light and Motion Vya Pro headlight and say it’s sufficient for urban riders or as a secondary/backup light at night.

Bontrager Flare RT
Taillight is compact yet bright

The Flare RT features three different flash modes and two steady modes. The flash modes are: day flash (90 lumens, 6 hr), all day flash (45 lumens, 12 hr) and night flash (5 lumens, 15 hrs) The two steady modes are day steady (25 lumens, 4.5 hr) and night steady (5 lumens, 13.5 hr). Although 90 lumens doesn’t sound like much, especially compared to the 200+ lumen taillights you can buy, the highly focused beam had excellent visibility even during sunny California days. For our testing we preferred to keep both lights in day flash and allowed the ambient light sensor to switch to the corresponding night mode. In this case, we think less would be more as we found many of the modes weren’t useful. We prefer the simplified approach of the Light and Motion Vya lights which simply have a day/night mode with the ambient light sensor deciding between the two. We found that we only used the daytime flash/night time steady for the headlight and daytime flash/ night time flash for the taillight. The various steady modes for the Ion 200 RT and Flare RT could easily be simplified to a single steady mode to reduce the number of modes.


Overall, we found that the Bontrager Ion RT and Flare RT packed an impressive punch despite their small size. The daytime flash modes worked well to ensure we remained visible during the day without the need for bulky lights. At night, the 200 lumen output of the headlight was good for urban riding (we would recommend higher output light for dark trails) and the 90 lumen taillight made sure we were seen. The ambient light sensor and Bluetooth connectivity also allowed us to simply put the lights on the bike and forget about them. If you’re looking for compact and high tech lights, the Bontrager Ion RT and Flare RT are definitely worth a look.

Disclaimer: The product for this review was provided by Trek Bikes. The views expressed on this website are solely those of the authors and are here to help people make an informed choice before a purchase. The authors or the blog itself does not get any monetary compensation from the product manufacturer or third-party websites/vendor links that are posted here.

4 Replies to “Daytime visibility without bulk with the Bontrager Ion and Flare RT lightset”

    1. You should contact Bontrager customer support for a replacement. The lights should handle rain. I suspect the rubber cover over the USB port may have been loose or there was a manufacturing issue with your light.

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