B'Twin VIOO 520 USB front light

The B'Twin V100 520 front light is a safety model with decent output and really distinctive, battery sipping flashing modes. However, lights with proper lenses are better bets if you want to be seen round town.

Given the cube shape and funky colour, the V100 520 could easily be the result of a passionate tryst between Knog's Blinder 4 and Gecko series. Inside the reassuringly thick rubberised body-cum-bracket lives four perky diodes and a lithium-polymer cell charged through a USB socket, reckoned to enjoy a lifespan of approximately 500 charge cycles before becoming bin fodder.

USB rechargeable lights are usually highly water-resistant rather than fully waterproof. However, the port on the V100 520 is well sealed and a two year warrantee should render other misgivings academic. It takes 2.5 hours to charge from a wall charger, ten minutes or so longer from a laptop or similar.

The straps can be a weak spot on rubbery one-piece lights. Thankfully, these have retained their elasticity despite being regularly ported between standard and oversized bars.

Powering up is simply a matter of depressing the reassuringly positive centre mounted switch for two seconds whereupon it defaults to steady mode. Subsequent prods engage the distinctive flashing and strobe patterns. Unless you get very unlucky it's unlikely to turn on wile it's in your posket or bag. Conversely, toggling down on the fly requires practice, especially wearing winter weight gloves.

The steady mode is certainly bright. It manages 3:27 and in a pinch, it's adequate for limping home following main system failure.

Indeed, urbanites might find it adequate for pub scoots, or hustling across town when paired to a second flasher. The first of these extrovert settings oscillates quite aggressively and B'Twin reckon visibility is 600 metres plus.

Perky diodes cast these further than expected but I'd say the reach is nearer 450m on a very clear night and 250m through neon-soaked town centres.

Two disco-strobe patterns are captivating and unique, and therefore brilliant for nailing driver attention when entering traffic flow or getting noticed by pedestrians using shared paths. Ours have returned between 14:27 and 15:19, fully charged. Only the slowest, pulsing mode has managed 17 hours.

Verdict

Surprisingly potent, funky looking and frugal, but very much a secondary/back up light

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