Mountain Bike Light Review: The Light & Motion Imjin 800

The Light & Motion Imjin 800 is compact and bright, with a claimed battery life of 2 hours on high. However, the battery life indicator is not visible when mounted to a bike helmet.

Light & Motion’s Imjin 800, sitting front and center with the provided helmet mount.

A reasonable person may look at a dark forest and think an unlit trip through the woods is a potentially risky proposition. But mountain bikers don’t see things the same way, and thankfully Light & Motion has a new lighting system to keep riders on trail, and out of the trees.

The Imjin 800 is Light & Motion’s newest offering, a long-lasting, compact bike light designed for those unwilling to let something as mundane as the Earth’s rotation about the Sun stop them from hitting the trail. But is the Imjin 800 a suitable substitute for the sun? Read on to find out.

A Lightweight Luminaire

Weighing in at just a hair over 230 grams, I never felt encumbered while riding with the Imjin 800. I mostly used the helmet mount with the battery pack strapped to the back of my skid lid, and I could hardly feel the weight. However, Light and Motion includes enough cable so the battery pack can be zipped up in a backpack, should the rider want to keep those lithium ions off the helmet. Light & Motion also includes a GoPro-style mount and a handlebar mount to further expand mounting options. The included 120V charger takes the battery from empty to full in about 3 hours.

One little light emitting diode is all that is needed to pump out 800 trail-illuminating lumens these days, and the efficacy of the singular LED is seriously impressive. Light & Motion uses a CREE LED, which produces impressively clean light on the trail. After trying a number of lights that put out variable, irregular light patterns on the trail, I was stoked to have consistent illumination that allowed me to see the trail clearly without feeling like my eyes were deceiving me. However, generating a wealth of light requires a substantial amount of power.

If the Imjin were able to defy physics and have a limitless supply of power, one could ride all night without any issues. However, since only so many electrons can be crammed into a given battery pack, there is a definite and non-negotiable limit to the run time of the Imjin light. Light and Motion says the Imjin 800 will last 2 hours on high, and unfortunately for this reviewer, this was confirmed the hard way while at a downward trajectory on a particularly spicy section of the aptly-named Predator trail at Tiger Mountain.

The Imjin’s battery pack and generous length of power cable. The included rubber strap holds the battery and cable securely, even when riding rougher trails.

Everything Was Illuminated

Without any perceptible warning, the four rock drops that were fast approaching my front wheel were thrown into darkness as the Imjin battery pushed its last bit of electricity to the LED at the other end. In the industry, we would describe this sudden turn of events as “suboptimal.” After a quick prayer to whatever mountain biking deity happened to be listening, I somehow found myself at the bottom of the drops in roughly the same shape as when I entered. I was able to toggle the Imjin back to life, only to have it cut out moments later.

When there’re enough electrons in the battery pack, the Imjin 800 produces some very smooth, natural light – much better than other lights I’ve tested in the past

Herein lies my main issue with Light & Motion’s offering. Mounted to my helmet, it’s impossible to see the battery life indicator. If there was a red light blinking somewhere on my helmet, I was unaware. Perhaps Light & Motion could add a low-power warning, like a dimming of the light or maybe a warning “flash off – flash on” to indicate the battery status.

After the somewhat exhilarating lesson on Tiger Mountain, I’ve since opted to run the Imjin 800 at one of its lower power settings to stretch my ride times and avoid sudden plunges into the abyss. Even in low power mode, which offers 200 lumens, the Imjin 800 (now more of an Imjin 200, for the pedantic) did a great job keeping the trail illuminated. Light & Motion claims the runtime at high (800 lumens), medium (400 lumens), and low (200 lumens) are 2 hours, 4 hours, and 8 hours respectively which, based on my tests, seems accurate.

At the lower power settings, I’ve been able to use the Imjin for several rides before needing a recharge. Truth be told, after more rides with the Imjin set to medium, I’ve found the light to be an exceptional performer in both light output and battery life. So I typically find myself setting the light to the mid-power setting and never touching it until I’m back at the trailhead. It’s possible to increase the life of the battery further still by using the Pulse mode, which promises 16 hours of battery life. This could work in an emergency, but truthfully it casts too much of a “club life” vibe, so I can’t say this mode is recommended for everyday riding. But your mileage may vary.

The Imjin comes with several mounting solutions, including a helmet mount, handlebar mount, and GoPro-style mount. With the handlebar mount, the battery pack and extra cable are strapped tidily to the top tube. Note the amber side lights, which are useful if you find yourself contending with vehicular traffic.


Overall, I’ve come away impressed with Light & Motion’s Imjin 800 mountain bike light. The battery life shortcoming I found initially was easily remedied by an adjustment of both expectations and light output. Even with the reduced lumen setting, the trails were illuminated enough to allow for plenty of higher-than-reasonable-speed antics out on the bike, which did wonders for alleviating the mid-week/mid-winter, no-ride blues.

Would I have loved to have a full 800 lumens for 4 hour rides? Of course, but short of either bending the laws of physics or doubling the size of the battery pack, the Imjin 800 had to be designed with some constraints. I think Light & Motion have struck a fine balance between overall weight and performance. However, I would appreciate it if they’d warn me before shutting off the light.

In short, one would be hard-pressed to find a better solution than the Imjin 800 ($200 MSRP) and its combination of light weight, performance, and run time. Just be sure that you’re fully charged before you charge fully into the night.

Thanks to Light & Motion for providing the Imjin 800 for review.