Topeak Highlite Combo USB Lightset

CANDELA The actual amount of light output at the source, similar to volume of sound coming out of a speaker in all directions. One candela = the light intensity of a household candle.

LUMEN The amount of light (light density) that reaches you at a set distance (1 metre) and angle, similar to how loud the sound would appear to you a metre away from the source.

LUX The amount of reflected light from a surface. If you shone a torch at a dark wall, LUX is the light coverage you can see reflected on the surface.

WATT A measurement of power (electricity) rather than a light output. LEDs are measured differently to household, incandescent and florescent bulbs.

What do you NEED to look for?

All lights have a focused beam so it is difficult to compare Lumens and Candelas.

COMMUTING Get the brightest light your budget can afford, with the best features.

OFF ROAD LIGHT A unit with at least 1000 lumens is a good benchmark (500+ is ok but hard to see at faster speeds.