Lighting question

[Ben98]

Hi there
Does anybody know if a 70 lux light will be bright enough for riding forest tracks and the light in the dark? ROSE only seem to quote lights in lux rather than lumens so I'm having a hard time converting

[whitestone]

Lux is actually more useful than lumens as it measures the light "on the ground". MTB lights are very wasteful as their beam pattern (well lack of pattern) throws a lot of the output light in to the sky - one reason why MTB lights aren't particularly pleasant for other road users. http://gemini-lights.com/explore/lux-and-lumens

RoadCC have a comparison tool that shows the light spread of many lights so you might want to look at that if you haven't already. Peter White cycles has a review of some lights: http://www.peterwhitecycles.com/b&m-hl.asp

I've a B&M Cyo plus which is, I think, 60 Lux. In use it's about as bright as a Hope Vision 2 light since the latter doesn't focus its beam.

[jameso]

I don't think it converts that easily but for reference my Edelux 2 is ~90-100 lux at 18-20 mph flat road pace and is incredibly good at lighting up the road, it's also really good at 10mph off-road where it puts out around 70-80 lux but at climbing speeds it gets a bit dimmer, down to about 35-40 lux based on the output graphs. So a consistent 70 from a battery light should be ok, it's likely that 70 lux is more useful than the 250 lumen Exposure Spark that I can do basic off-road on quite happily. 70 lux as a max for an off-road dyno powered light may get a tad low at 7-8mph though. All depends on the beam spread also, a well-spread 70 lux over a larger area is enough for most things, over a torch-like small round spot with no side-spread it'd be less useful.