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Gloworm XSV review

How does the NZ-based company’s range topping light perform out in the dark?

Our rating 
4.0 out of 5 star rating 4.0
GBP £289.00 RRP | USD $320.00 | AUD $389.00
Gloworm XSV

Our review

The Gloworm XSV is a great light with a bunch of accessories included. Pairing functionality with other Gloworm lights makes its ecosystem very attractive, too, but its high price and fairly focused beam keep it from scoring higher.
Pros: Long battery life; good mix of flood and spot lighting
Cons: Fairly focused beam as standard; high purchase price
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Gloworm has been producing lights since 2010 with the aim of making high quality, high performing lights at affordable prices. In the past I’ve tested its lower-powered lights, which have done well, but now, with a large selection on offer, I’m testing the top-of-the-range XSV — or ‘excessive’.


Gloworm XSV details and specification

Gloworm XSV
The XSV is supplied with plenty of parts and accessories.
Alex Evans

The three in-line Cree LEDs mounted in the light-head pump out a claimed 3,400 lumens with their standard spot light lenses. The unit has an IP67 water- and dust-proof rating and the head unit’s body has been CNC-machined out of a single block of aluminium.

Included in the box are two wide optic lenses that are user replaceable, with the also supplied Allen keys. On top of that, you get a GoPro-style mount with sticky pad and a 31.8mm bar clamp. There’s also a 35mm bar clamp that isn’t included in the box and costs £5 extra.

Gloworm XSV
Wide angle diffuser optics come with the light and are user-replaceable.
Alex Evans

You also get a wireless, two button remote that uses an O-ring to mount to the bars. Along with the included mounts, it’s possible to buy a Garmin-style mount for the light as well.

The separate battery pack uses four Panasonic cells that put out 50Wh of power and it has a battery life display on one end. The cable that attaches the battery pack to the light unit is 41cm long, but an 86cm extender cable is supplied.

Gloworm XSV
The remote can be used to control two Gloworm lights.
Alex Evans

It has seven default modes operated by one single button on the rear of the light, or with the remote’s buttons once paired. It is possible to customise the light’s outputs should you desire.

Although I only tested one light, if you have multiple Gloworms it’s also possible to pair a single remote control to two lights either separately, each with a button or both using the same button.

Gloworm XSV
The three LEDs, even without the diffuser lens, offered a good spread of light.
Alex Evans

Like most lights currently on the market, it has thermal protection that constantly checks heat, power and output to stop its electronics getting damaged from the heat created by the LEDs.

Gloworm XSV performance

The three LEDs have a great amount of power with plenty of range, similar to most lights that have a claimed 3,000 lumen or above output.

The light emitted is bright enough to highlight even the gnarliest but slightly straighter singletracks as if it’s daytime with a good mix of flood and spot lighting, even with the standard 17-degree spots installed over all three of the LEDs.

Gloworm XSV bicycle light beam pattern
The Gloworm XSV’s stock 17-degree optics create a gradual cut-off beam but side spread is fairly limited but overall brightness does mitigate this to an extent.
Simon Bromley

The spot is fairly focused in front of the bike, but the light is powerful enough that it also has a reasonable beam spread. The light’s forward range isn’t as far as some lights though and the beam’s cut off point is very gradual — there isn’t a distinctive line where light turns to dark.

I did notice that when my front wheel lifted or hit jumps the light dazzled me. There’s no hood or cover over the top of the LEDs and even though the lenses are slightly recessed into its body, this isn’t enough to stop it occasionally dazzling.

Gloworm XSV
The tool-less bar clamp is great if you swap your light between bikes.
Alex Evans

I also found the side-to-side spread fairly limited with the factory-installed spots. This meant that spotting lines around turns wasn’t easy and some obstacles jump out at you — although the light’s overall brightness does mitigate this a bit.

The LEDs’ hue is a good mix of white and yellow, which makes it quite easy to see what’s ahead and makes the terrain pop without causing eye strain. The beam can cast shadows over some obstacles but I think that this is more to do with the spot light lenses rather than colour.

At full chat the light lasts for 1 hour 50 minutes, a full 20 minutes longer than it’s claimed to last.

The tool-less clamp is easy to attach and remove from the bars and I liked all of the other accessories included with the light.

Mounting it to the various clamps is easy but the small screws you need to use on the other mounts can be a bit fiddly.

Gloworm XSV
The single attacment bolt makes adjustment easy, but I struggled to get it tight enough.
Alex Evans

The bar clamp attaches to the side of the light and relies on rubber O-rings to secure it in place. It’s very easy to overtighten the screw in a bid to try and stiffen up the clamp connection to stop it twisting. But the O-rings mean it’s tricky to actually get the connection to go stiff. Plastic or metal washers or shims would help here.

Despite this hard-to-tighten connection, the head unit’s low weight means it doesn’t rotate, twist or bounce when riding over rough terrain and it surprised me with how stable it is when mounted to the bars. Because it’s so light, it’s entirely suitable to use on your lid, too.

Gloworm XSV
There’s a life indicator on the battery pack that’s illuminated when you plug the light in.
Alex Evans

The cable that attaches the battery to the light unit uses a push-fit connector and was long enough to not prohibit where I mounted the battery. The included remote is fantastically easy to mount, pair and use even when you’re pushing it in anger.

The light’s lack of mode indicator is frustrating though, but its operation is relatively simple and the number of default modes make it hard to get too lost in the mode schema.

Gloworm XSV
The XSV’s battery pack isn’t very big.
Alex Evans

The charge indicator on the battery is fairly clear to read but it’s not something you’ll be able to glance at while you’re riding. The light’s button does change colour and finally flash once the battery is near the end of its charge, which is handy.

Gloworm XSV bottom line

Gloworm XSV
The head unit is well made.
Alex Evans

The Gloworm XSV is a great performing light with a bunch of accessories and mounting kits included in the box, even different lenses, making it particularly adaptable.

Compatibility and pairing functionality with other Gloworm lights makes the ecosystem very attractive, too.

Its high price, some small mounting quirks and fairly focused beam — as standard — keep it from scoring higher, however.

Gloworm XSV
Just open the clamp and the light comes off the bars.
Alex Evans

Between testing and this review being published, Gloworm launched a new, brighter version of the XSV which should, in theory at least, address some of my concerns. The new light is claimed to be 30 per cent brighter than the outgoing model and is expected to cost about the same.

How we tested

Testing lights objectively is a tough task. While it’s entirely possible to measure the number of lumens a light emits, there are a lot more variables that dictate how much of that light illuminates the trail. The colour of the light, its beam pattern and lens type have as much effect as the outright power.


With that in mind, we haven’t measured the number of lumens each light emits for this test. Instead, we’ve assessed how the light performs by describing the beam pattern, its colour and overall performance, while also measuring run time on the most powerful setting.

Product Specifications


Price AUD $389.00GBP £289.00USD $320.00
Weight 402g – Total weight
Brand Gloworm


Features Clamp weight: 19g
Head unit weight: 122g
Battery weight: 250g
Run time: 1 hour 50 minutes (max power)
Integrated battery no
Light type Front
Output (lumens) 3400
Remote switch Yes