Even as bike lights become smarter and brighter, they all share one major weakness… the battery. Whether you’re using traditional AAA batteries or the latest high capacity rechargeable Lithium Ion cells, batteries either need to regularly be recharged or replaced. For a more permanent solution to bike lighting, the primary option has typically been dynohub powered lights. However, these use friction to generate electricity and are often bulky in size. Reelight has developed a variety of magnetically powered non-contact lights that offer an alternative solution. Today we’ll be looking at the Reelight CIO lightset which includes a headlight and tail light that utilize simple spoke magnets to provide power.

The Reelight CIO bike light set offers a battery free and worry free design that lets you simply mount them on your bike and forget about them knowing you’ll always have extra visibility.

The CIO lights were originally introduced on Kickstarter back in 2017 and have become one their most popular models. In this review we are looking at the latest third generation of the CIO lights which has improved the optics for a wider beam and fast charging. The friction-free design means aside from the 60g weight per light, there is little downside to using the lights. With the low lumen output of the lights (14 and 9 for front/rear), the CIO lights are definitely ‘be-seen’ lights or secondary lights for additional visibility.

CategoryBicycle Head + Tail Light
Rating 8.3/10
Retail Price $59
Measured Weight (in g)  60 / 60 (headlight / taillight)
Likes+ Battery free
+ Theft resistant metal wire mounts
+ Continues to flash for upto 2 minutes when stopped
Dislikes– Sensitive positioning
– Low lumen per $ vs other lights
– Elongated form factor
Where to Buy (US)Reelight


The CIO lights are packaged in a compact environmentally friendly cardboard box with well designed graphics.The package has a magnetically held lid.that covers a window to allow you to view the lights inside the box.

In the box you’ll find:

  • CIO headlight
  • CIO tail light
  • Instruction manual
  • 2x spoke magnets
  • Small coin-like installation spacer
  • Allen key tool for mounts

Note: The installation spacer and mount tool are glued to the inside of the instruction manual so do not throw away the instructions before removing them. Thanks to the battery free design, this is one of the few lights that doesn’t include a USB charging cable.


One of the clever design details Reelight has incorporated into the CIO lights is the secure wire mount design which Reelight refers to as ReeMount. Despite having reviewed dozens of lights at this point, the CIOs ReeMount design is the first we’ve come across. Both the headlight and fhe tail light use the same thin metal wire that wraps around the bike frame and hooks into the base of the lights. This is far more durable than the common rubber straps that are typically used for mounting and is meant to be more permanently installed on the bike. To adjust the tension on the wires, you use the supplied Allen key tool and rotate the inset bolt on the bottom side of the housing to loosen or tighten the tension. 

Reelight CIO lightset - magnet
Reelight includes a small tool to adjust the tension on the theft resistance metal wire mounts

Don’t worry about losing the adjustment tool though, as a simple 2.5mm Allen key works just as well. The tool itself is simply a short Allen key with a plastic handle that makes adjustments more convenient. This is a theft resistant design, or as we like to call it “security through obscurity.” The metal wire is easy to clip with small wire cutters but would render the lights useless, and even though a standard Allen key can be used, most thieves wouldn’t know how the mount works. We prefer this design over other theft resistant lights that use special bolt heads that require a specific tool. This design is clever and also really keeps the lights in place even over potholes or curbs.

Reelight also includes the necessary spoke magnets which are larger than traditional cadence magnets. The spoke magnets attach to standard round spokes, so if you have bladed spokes you won’t be able to utilize these lights. To mount the magnet it uses a simple bolt that uses the same adjustment tool to tighten down on a spoke.


The Reelight CIO offers a unique solution to adding visibility to your bike by eliminating the need for a battery and offering a secure and theft resistant mount. Visually, the headlight and tail light look nearly identical aside from the lens colors as they utilize the same housing and mount design. Due to the magnet contact surface being positioned to only one side of the housing, the CIO lights can only be mounted on one side of a bike and should be placed on the side facing traffic for optimal safety (on the left side of the bike for countries with left hand drive cars). Installing the lights requires positioning the contact surface of housing and spoke magnet within a specific tolerance. Reelight provides an installation spacer that makes this process easier, and the lights can swivel upto 35° to help position them. As a result of this magnet design, the CIO lights have a somewhat awkward elongated design that allows them to be placed near the wheel spoke. We were concerned that the lights could potentially fall into the spokes due to the positioning, but found that the mounts are secure enough to keep the lights in place.

Reelight CIO lightset - lens
The large lens on the CIO lights result in excellent side visibility

The user interface is very simple for the CIO lights as there are no buttons or batteries to replace or charge. Once you start to ride, the CIO lights automatically start flashing and can even continue to flash for upto two minutes after you stop as they hold a temporary internal charge. This design really allows you to focus on riding and forget about the lights as you don’t need to turn them off or cycle through different modes. Cutouts on the outer portions of the lens also improve the side visibility by dispersing the light which allows you to be seen even from side angles. Another thing to note is that the supplied spoke magnets only work with standard round spokes and are much larger than those that are typically used with bike speed sensors.

COMPARISON – Planet Bike Spok USB / Magicshine Seemee 30

One of the big advantages of the CIO lights is the contact and battery free design compared to traditional USB or battery powered lights. How does this equate to real world riding? We compared the lights to a few other battery powered equivalents the Planet Bike Spok USB and the Magicshine Seemee 30 lights. Both of these lights cost less than the Reelight and are USB rechargeable. Also, both battery powered lights are more compact, offer more flexible mounting options, and have higher output. However they both have single level battery indicators and have to be manually turned on and off. Riding with the CIO is more similar to the more expensive Light and Motion Vya Pro or the Bontrager Ion 200 RT and Flare RT lights as you can simply start riding and let the lights automatically turn on and off. As secondary lights, the CIO eliminates the typical “range anxiety” we have with battery levels and offers more permanent mounting (albeit less convenient).

Reelight CIO lightset - form factor
The CIO has a larger form factor than traditional battery powered lights


The buttonless CIO lights, not surprising, only feature a single flash output mode. There is a single LED mounted on the front of both lights with a transparent lens that extends over the entire face for better side visibility. The flash mode has a standard repeating one-off pattern that works well to draw attention at night. According to the datasheets Reelight provides on their website, the headlight and tail light have only a 14 and 9 Lumen output at 15 km/h. This means the CIO lights aren’t particularly bright and are a ‘be seen’ type light that ensure you’re visible but don’t light up the road. Also with the magnet powered design, the runtime for the flash mode is infinite as long as you stay in motion.

Once you have ridden the lights for a minute or so, they also store a bit of charge internally. This means as you come to a stop, they stay illuminated for upto 2 minutes. That ensures you remain visible when stationary at stop signs or traffic lights which is a great built-in solution. The lights are designed to be left on your bike which means even though they aren’t that bright for daytime use, the flashing mode still helps draw attention to you.


Overall, we found that the Reelight CIO lights are a clever solution to a battery free bike light for extra visibility. The simple spoke mounted magnets allow the headlight and tail light to take advantage of the electrical fields generated by the rotational motion to provide infinite runtime. Even though the lights aren’t particularly bright, the secure and theft resistant mount design allows you to leave the lights installed on your bike year round. Installation is straightforward and only requires a little patience to align the spoke magnets and lights, with the provided spacer helping to speeden up the process. The lights are more expensive than other battery powered lights on the market, but the clever mount design and magnet power offer a lot of advantages and allow them to be permanently mounted on your bike. The CIO lights buttonless and battery free design make them excellent secondary lights you can install once and then forget about, knowing you’ll always have extra visibility.

Disclaimer: The product for this review was provided by Reelight. 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.

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