Gloworm XSV Bike Light Packs 3400 Lumens, Adjustable Beam Shape [Review]

There are a lot of lights for mountain biking at night on the market, and they’re all seemingly pretty basic: light plus battery equals extended season. Many of us probably thought the same thing about bikes when we started riding, but we quickly learned entry-level bikes leave a lot to be desired in terms of performance. Gloworm is the Ibis of the bike light world, and their XSV light offers a huge upgrade for riders still running entry-level lights.

Bright, bright baby

I’m the first to admit few of us actually need 3,400 lumens of brightness for riding trails at night. Then again, I don’t need a Kashima-coating on my fork either — but it makes a good fork feel even better. It’s rare that I need that much light on the trail, but it does come in handy when scoping a line that drops off into darkness or pinning it to catch up with the rest of the group after a bathroom break.

Gloworm claims the XSV will last 1.5 hours on full brightness with the included battery. Most riders won’t need to run the light on high for the entire ride, which leaves plenty of extra capacity at the lower light settings. Most of my night rides last about 3-4 hours and I’ve yet to reach the limits of the battery. For casual riding, the low setting paired with a second light is generally enough. I flick the light to medium for descents and only rarely kick it into high mode. There’s also a “super dim” mode that works well when you just want to be seen (like on the road).

Maximum brightness3400 lumens
Battery life1.5 hours on high
Brightness settings4: super dim, low, medium, and high
Weight332g (light plus battery pack)
Price$320 USD (available from Gloworm and JensonUSA)
Key featuresWaterproof to IP67, 3 Cree emitters, remote control, 4 hour charge time
You’ve got options when it comes to optics.

Consumers tend to focus on how bright a light is in terms of lumens, but if the light isn’t shining where you want it, much of that power is wasted. The Gloworm XSV features a unique, swappable optics system that allows the rider to dial in the preferred beam pattern. For example, the honeycomb optic smooths out the hotspot riders see at the center of the light output which can be easier on the eyes. And the wide optic helps improve peripheral visibility on narrow trails.

The handlebar remote is simple to install and use with just two buttons — up and down — to toggle between light settings. It’s easy to sync the remote to another Gloworm light as well, so riders can control both their bar- and helmet-mounted lights together.

Form factor

The XSV separates the light from the battery pack and ships with an extension cord which gives riders multiple mounting options. Bar and helmet mounts are included in the box, utilizing a GoPro-style attachment system. The XSV light head is fairly large, but it’s not too heavy to mount on a helmet if that’s where you want it. I mostly ran mine mounted to the handlebars using the 35mm-diameter bar mount which is sold separately.

The battery has an LED indicator to let you know how much juice is left when it’s running, or how much longer until it’s fully charged. Depending on where you have the battery mounted during your ride, you might not be able to see the battery life indicator, so the Gloworm XSV also flashes the light as a warning when the battery is getting low. It’s smart, well-thought-out features like this that separate this light from the entry-level.

Since I generally mount the XSV to my handlebars, I strap the battery to the underside of my down tube near the intersection with the head tube. Gloworm includes a rubber shim to place between the battery and the frame to prevent slippage and to protect the bike. However, I found it difficult to get the stretchy velcro strap tight enough to hold the shim in place. During an early ride I made a mental note to hot glue the shim to the battery pack, but of course when I got home the shim was gone, no doubt dropped somewhere along the trail. The shim is a nice touch for mounting the battery to a bike, and I guess the rubber might get snagged when taking the battery in and out of a jersey pocket in helmet mode so I get why the two aren’t glued together. Still, I’m bummed that I lost it so easily.

Seared bolt, left. Loose cable, right. The first was user error, the second was a production issue that has been addressed.

The bar mount utilizes a simple bolt with a pair of tiny rubber gaskets that, as it turns out, must be installed correctly. I failed to put them on in the right order, which caused me to overtighten the bolt, which became stuck inside. When I tried to back it out, the bolt sheared off. As always, read the manual, and if a screw doesn’t go in smoothly, back it out and see what’s wrong before doing permanent damage.

While testing an early sample I had an issue with the wire coming loose from the light head which caused the light to stop working completely. Bruce from Gloworm shipped a replacement right away and noted this was caused by a production issue that had been addressed for new units going forward. This is the type of customer service and continuous refinement buyers should expect from any high-end mountain bike product like the Gloworm XSV.

Bottom line

Some might be quick to point out that there are much cheaper bike lights available, and while that’s true there aren’t many lights that perform better or offer as many features as the Gloworm XSV. For riders who expect a high quality product and a great experience, the XSV is a solid buy.

⭐️ Find the Gloworm XSV bike light at Gloworm and JensonUSA.

Thank to Gloworm for providing the XSV bike light for testing and review.

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