Exposure Diablo Mk 12 review

Exposure’s second most powerful helmet light is super neat but is it worth the high cost?

Exposure Diablo Mk 12 review
(Image: © Guy Kesteven)

Bike Perfect Verdict

Super neat and powerful with innovative ‘tap’ power changes make the Diablo an impressive helmet or fast bar torch, but battery life is short and TAP technology needs careful tuning


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    Brilliant universal helmet mount

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    Powerful, slightly spread beam

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    Enough spread for fast/far bar use

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    TAP switching is clever if set right

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    Multiple modes

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    Comprehensive supplied accessories

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    Supplementary batteries are available

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    Sync Bluetooth option

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    UK factory and event support


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    High price

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    Short battery life

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    Noticeable center spot in the beam

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    Limited run time communication

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    TAP can be too sensitive

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    No wireless control

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    Make sure you use the tether

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As far as the best mountain bike lights go, there are seven different helmet lights in the Exposure range with the newly uprated Diablo sitting in the second most powerful spot, complete with an evolved range of accessories and a super neat helmet mount. It’s versatile enough to use as a bar light, too. Run time is short though and you need to tune the cunning TAP technology to your riding style, as it lacks wireless control or custom tuning. Oh, and make sure you tether it, too.

Design and aesthetics

In terms of design, the Diablo is basically a cylindrical torch, albeit a very nicely UK-manufactured one with machined casing including cooling rings at both flared ends and three anodized color options. Three XPL2 LEDs behind slightly detracting lenses emit a maximum of 1,800 (measured not theoretical) lumens. That gives some spread to the beam outside of a noticeably brighter center spotlight so it actually works fine as a road/gravel or less techy/twisty MTB bar light using the supplied O-ring mount. While the center of the beam has a clear step in terms of brightness, the three overlapping light sources mean no nasty edges or fluctuations to disturb detail perception, and while it might not seem as bright as some lights of a similar power output, the quality of vision is very good. 


The 3,500mAh Lithium-Ion battery only gives enough power for a little over an hour of maximum power run time. The eight menu options only default to half-power as the second brightest setting, which is definitely a bit dim for pushing the pace. Battery feedback is just limited to a traffic light of color change from the single LED on the back of the lamp, which you’ll have to rely on riding buddies to keep an eye on if you don’t want to keep taking your helmet off. 

The Exposure answer is to engage the TAP technology setting via the OMS (Optimum Mode Selector) button hold menu. This lets you change the power setting by tapping anywhere on the light - or even the helmet in the most sensitive setting - rather than trying to find the small rounded button on the back. You need to be careful to select the right setting for the level of riding you’re doing though as we found the light could switch modes just with the helmet shake on rough descents or bigger drops in the most sensitive and medium settings, which is the last thing you want. 

The other option is to buy the Diablo Sync where you can tune the different output levels from your phone via a Bluetooth link. That version has a shorter run time despite the same output and battery, and it’s even more expensive at $325.10 / £265. That means we (and other Diablo/Joystick light users we ride with) generally end up supplementing the onboard battery with the 1,700mAh or 3,400mAh ’support cells’ that plug into the Smart Port on the back of the light to boost run times. 

This port is also where you plug in the supplied fast charger which will have you ready to go again in around four hours. Alternatively, you can use the USB lead which takes a lot longer but is useful for top-ups at work, or when traveling.

Low weight makes the Diablo unobtrusive in terms of neck load and it’s supplied with Exposure’s signature double-disc helmet mount, which is frankly brilliant. The two conical discs sit inside and outside of the helmet vent, clamping in place with a plastic bolt that can snap in a heavy crash to stop penetration injuries. It’s supplied with two lengths of bolt for different depths of helmet and it doesn’t interfere with internal MIPS sheets either. The ball and socket mount for the light itself allows full aiming accuracy. The whole setup stays impressively secure on rough trails too, so there are none of the distracting rattles that plague most strap-on lights. The light can be knocked out of the clip by overhanging branches or in crashes though, so we’d definitely use the included lanyard to tether it to your lid as insurance. If you’re UK-based, Exposure's direct factory support and on-site presence at most big after-dark events is also a significant plus that helps offset the high price long term.


It’s definitely very expensive compared to similar power lamps from other brands and conspicuously costly compared to general use high power LED torches. If that's the case, it's probably worth taking a look at our guide to the best budget mountain bike lights

That said, the details of the Diablo in terms of light quality, neat mounts and manufacturer support definitely elevate it to another level of user-friendliness though. If you set it right the TAP technology is great for offsetting short run time and limited preset menu options, too. 

Most long ride fans are still probably going to want to add a supplementary battery though and we think Exposure is missing a trick by not having a wireless link system that lets you connect it to one of its bigger bar lights in terms of power matching or just a wireless switch to control the light from your bars.

Tech Specs: Exposure Diablo Mk 12

  • Price: $329.99 / £215
  • Weight: 131g (121g light, 10g helmet bracket)
  • Power: 1,800 lumens max
  • Battery: 3500mAh
  • Run time: 1hr 10mins at max output (averaged over three runs)
  • Colors: Gunmetal (tested), oil slick, black
Guy Kesteven

Guy has been working on Bike Perfect since launch in 2019. He started writing and testing for bike mags in 1996. Since then he’s written several million words about several thousand test bikes and a ridiculous amount of riding gear. To make sure he rarely sleeps and to fund his custom tandem habit, he’s also penned a handful of bike-related books and talks to a GoPro for YouTube, too.

Current rides: Cervelo ZFS-5, Specialized Chisel, custom Nicolai enduro tandem, Landescape/Swallow custom gravel tandem

Height: 180cm

Weight: 69kg