Bike Lights- Lumens, Lux and watts

jerry3571

I bought a Smart 35 front light and have been impressed by the power of the thing (when I turned it on I actually said "f*ck me!" due to the amount of light. )
I like that it has the use of batteries as "in-built" batteries last a year or two and then die a death meaning a new light so.... I was looking to buy another just to make sure I can see extremely well in the dark.
Problem being comparing the different lights on the market is tricky with Lux, Lumens and watts and maybe even candles being described. I think 100 Lumens= 1 Lux but really this is all guesswork.
I am ok to buy another of the Smart lights but I'd like to see if there's something similar but more powerful.
Any words of wisdom?

Cheers Jerry

yeachan153

The smart 35 lux isn't 3500 lumens!!

jerry3571

Ok, any ideas? I am writing out of confusion here.
A Nightrider Mako 2 is 2 watt and 130 Lumen. How the hell is anyone suppose to compare? Bonkers!

I tried to use a conversion site -
http://www.unitconversion.org/illuminat ... rsion.html

and used Wikipedia for "Lux" where I got the ratio from (just read this and I'm more confused)-
http://en.wikipedia.org/wiki/Lux

Tricky one!

Thanks Jerry

thescouselander

Most of the time the different units aren't directly comparable and you cant convert between them. Even if you could I still think they're misleading. Probably the best way to understand the performance of a light is to see it in action for yourself.

I happen to own a Mako 2 Watt - I could try and capture some pictures of how it performs if you like although I'm not sure how useful that will be.

cougie

This may help http://eddys.com/articles/how-bright-is ... ght-ig493/

But if you want bright and cheap - look out for the ultra fire 501 torches. Amazing kit and ridiculous value.

Ouija

Might want to look at this.http://www.torchythebatteryboy.com/p/bike-light-database.html

tim_wand

Bump get rid of Trellstemmer

jerry3571

That's a photo of my smart Lunar 35 Lux light. I had to dull the photo a little to make it look how I saw it.
Thanks for the other websites; great stuff!!!

-Jerry

sungod

lux, lumens, candelas, and watts all measure different things, there's no way to convert between lumens and lux without knowing other details such as beam shape and angle, simplifying and making some bikey assumptions...

lux is a measure of how much light falls on an illuminated surface is, sometimes you may come across ye olde foot candle (not to be confused with candles, candelas, candlepower, etc.), one of these is just over 10 lux

whereas lumens measure how much light is emitted by a source

1 lux = 1 lumen per square metre

1 lumen = 1 candela per steradian, don't even go there, candelas are an unhelpful way to describe bike lights, outdone only by...

watts, typically refers to the maximum power rating of the led(s), it gives no indication of how much of the energy ends up as useful light (as opposed to heat, or light at wavelengths you can't see), it's probably the most useless specification there is for a bike light, 100% marketing puffery

in practical terms, a 100 lumen source that puts all the emitted light onto a 1 square metre surface will illuminate the surface at 100 lux, but the same 100 lumens spread over a 10 square metre surface will illuminate it at only 10 lux

light manufacturers dont usually give enough info to tell how widely their lumens are spread, lights that quote a figure in lux usually base this on the area illuminated at a distance of 10m from the light, but unless you know the area covered, it's still not telling you anything really useful

if you imagine beam shape on the road, with an illuminated area of, say, 20 square metres, you could estimate 10 lumens will give you 0.3 lux (it'll be more centrally, less at the edge, and i'm allowing 0.2 lux lost as spillage)

very roughly speaking, daylight (not direct sun) is maybe 15,000 lux, overcast day 1000 lux, an office is lit at around 400 lux, really dark overcast day 100 lux, living room might be 50 lux, twilight 10 lux, full moon less than 0.5 lux

so using the 20 square metre estimate, aiming for 20 lux, you'd need over 650 lumens, that's quite a lot

if you want to illuminate the road at night for riding *fast*, you may need a light with much more to see well far enough ahead for safety, but it depends on beam shape, if the thing is lighting up the treetops then a lot is being wasted

if you are going slower and just want to be easily seen, then 100-200 lumens will make you stand out ok on quieter roads, but in city traffic there's so much other light that even this may not be noticed by drivers, this is where a combination of a bright fixed light plus a flashing one can be useful

jerry3571

Thanks for that. Glad you have some understanding of this. Nightmare!! :?

-Jerry

Ouija

Stanley222 wrote:

Ouija wrote:

Might want to look at this.http://www.torchythebatteryboy.com/p/bike-light-database.html

There's some great lights on here but where do you buy them?!

That guy sells a lot of the ones he likes on ebay. http://www.ebay.co.uk/sch/big_f_d_d/m.html?hash=item1c223f6648&item=120833664584&pt=UK_SportsLeisure_Cycling_Bike_Lights&_trksid=p4340.l2562

Basically all the batteries, holders, chargers and other stuff that he's tested and found to work better than most of the similar looking stuff you can get from China at silly prices. Often cost a bit more but i'd rather get from a U.K seller.

Dudes away on holiday until January so it's not worth ordering anything just yet.

Mettan

jerry3571 wrote:

I am ok to buy another of the Smart lights but I'd like to see if there's something similar but more powerful.
Any words of wisdom?
Cheers Jerry

There are a variety of Ebay ''UK'' sellers selling the XM-L T6 501b/502b/C8 torches - (double-check relevent sellers on Ebay UK, and make sure they've got UK stock for fast shipping first though) - if you've already got a Smart 35, then any one of the above torches would make an excellent complement - (you can get them for £14 upwards) - for batterires, get yourself a pair of Trustfire flames, or maybe Yezl 2400/Xtar 2600 - chargers can be had for ~ £5 - £15 on Ebay itself - Xtar does a good one for £14.99 on Ebay, (but the cheapie 5 quid ones do usually work ok if your on a budget) - torch mounts can be had for ~ £4.

My current setup includes two XM-L T6 502b's and one XM-L T6 C8 - the 502b's give massive sub 20 metre flood whilst the C8 gives big, up to 50 metre throw with usable spill (the C8 can throw alot further, but in terms of a usable road-beam it can illuminate 30-50 metres comfortably) - a great combo.