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Specialized Flux 850 front light review

Double-beam light with high waterproof rating

Our rating 
4.0 out of 5 star rating 4.0
GBP £95.00 RRP | USD $80.00 | EUR €130.00 | AUD $190.00
Specialized Flux 850 front light for road cycling

Our review

Solid construction, slick operation and a quality beam pattern combine to make the Specialized Flux 850 worth the investment
Pros: Beam quality; ease of use; construction
Cons: No lateral adjustment
Skip to view product specifications

Specialized’s Flux 850 Headlight is clearly designed to help you be seen as well as see, with 180-degree visibility courtesy of bright side lights, which is particularly helpful at crossroads or T-junctions.

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Its dual-beam construction pairs a spot and a wide optic in order to combine focused reach with a broad spread of light.

A waterproof rating of IPX 7 technically means it can withstand submersion, in practice hopefully not, but it’s a reassurance that it will cope with the very worst weather.

Specialized’s ‘Mode Shift’ operation allows you to switch between steady modes without cycling through flashing, and you can go from low steady to high steady in a single click.

Specialized Flux 850 front light for road cycling - beam shot
The Specialized Flux 850 is bright enough for unlit roads.
Russell Burton / Immediate Media

The beam pattern has a decent reach and spread, with no distinct gradient or stepping at the periphery, and while the top of the beam has no obvious cut-off line, it doesn’t spill excessive light upwards either.

The 850 lumens is bright enough for unlit roads and one of the advantages of this light is the easy shifting between modes.

Single successive clicks will take you up and down steady modes. A two-second hold switches it into the flashing cycle and then back again.

I found it a convenient feature on routes that took me from a well-lit area, where I ran a low beam, to darker lanes that needed a quick switch to more power.

Specialized Flux 850 front light for road cycling
The mount is easy to fit and proved to be secure.
Russell Burton / Immediate Media

Fitting the Flux 850 is a cinch. The solid aluminium clamp bracket uses a quick-release that takes a matter of moments to fix or remove.

The offset position of the light means that it can be positioned above, below or in front of your bike’s bar – whatever works best with any given combination of bar-mounted gadgets – but once in the mount, there’s no lateral movement.

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The Specialized Flux 850 is a high-quality light with a solid construction that delivers a bright, consistent beam and user-friendly operation, even on the fly.

How we tested

With darker nights upon us, we put eight front road bike lights to the test.

Unlimited budgets are a luxury, though, so each light is priced under £100 and has a brightness of between 500 and 1,000 lumens (with one measured in Lux). 

As well as brightness, we considered beam performance, run times, mode options, any waterproofing claims, as well as the unit’s construction and other features, such as mount types.

The lights were all tested in urban conditions and on unlit and rural roads.

Also on test

Product Specifications


Price br_price, 5, 3, Price, AUD $190.00EUR €130.00GBP £95.00USD $80.00
Weight br_weight, 5, 6, Weight, 181g – with bracket, Array, g
Brand br_brand, 5, 10, Brand, Specialized


Features br_Features, 11, 0, Features, Lux @ 5m high beam: 175
Run time: 90 minutes at max power
IP/waterproof rating: 7
Battery capacity: 2600mAh
Modes: 8 – High, Medium, Low, Daytime Flash, Steady Flash, Very Low, Super Low
Integrated battery br_integratedBattery, 11, 0, Integrated battery, Yes
Light type br_lightType, 11, 0, Light type, Front
Output (lumens) br_outputLumens, 11, 0, Output (lumens), 850