Lux or Lumens?

[Fishy]

So, I'm in the process of choosing my first e bike, and one thing that's very important to me is good lights, as I live in the middle of nowhere, (no street lights, or ambient lighting from houses etc.). There are a couple of Cube models I'm weighing up, but one's front light is described as 20 lux, the other as 180 lumens. Which would be better?
Is there actually any way to tell, other than seeing them both in action?

 

[vfr400]

Chinese lumens are the best. You get a lot mote of them for your money - if you believe the adverts.

180 lumens is not bright at all. You should be looking at thousands, like this one with 45,000 lumens. That's 250 times brighter. Even if you allow for a bit off Chinese exaggeration, say 10 times, it's still 25 times brighter.

You should look for a light that has one or more Cree T6 emitters. One emitter is enough for most riding, maybe three if you go on unlit roads or cycle paths. Any more is over-kill and only flattens your battery quicker.

Back lights are not so critical. These ones arent bad and the 2 AAA cells last for ages, but the brackets break when you try to remove them.
https://www.ebay.co.uk/itm/Rear-Light-Flashlight-Lamp-Red-Laser-LED-Bike-AAA-Battery-Support-E3R1/282653635313?epid=1949317283&hash=item41cf7832f1:g:sVUAAOSwT4tZur-j&redirect=mobile

Lumens is how bright a light source is and lux is how much light lands on a surface.

 

[Fishy]

Quote ......

"Lumens is how bright a light source is and lux is how much light lands on a surface."

Yes, but without giving a distance, surely a lux rating is meaningless?
20 lux at 1mtr, is going to be completely different to 20 lux at 10mtrs, or have I got that wrong

 

[soundwave]

http://www.magicshine.com/product/mj-908-bicycle-light-combo/

 

[vfr400]

Quote ......

"Lumens is how bright a light source is and lux is how much light lands on a surface."

Yes, but without giving a distance, surely a lux rating is meaningless?
20 lux at 1mtr, is going to be completely different to 20 lux at 10mtrs, or have I got that wrong

Correct.

 

[Woosh]

Lumens are the units of how much light is produced by the LED, typically, you get about 100 Lumens to 200 Lumens per WATT, so a 5W LED light would give about 700 Lumens on average.
The light is focused to a small area, say 10SQM. Lux is the unit of illumination. So a 5W LED torch produces700 Lumens, if focused onto a 10 SQM area will give you 70 Lux. Bright enough for country lanes.

 

[Woosh]

20 lux at 1mtr, is going to be completely different to 20 lux at 10mtrs, or have I got that wrong

they look just as bright.
20 Lux at 10M need a light source 1,000 times brighter than one that gives 10 Lux at 1M.

 

[Fishy]

Lumens are the units of how much light is produced by the LED, typically, you get about 100 Lumens to 200 Lumens per WATT, so a 5W LED light would give about 700 Lumens on average.
The light is focused to a small area, say 10SQM. Lux is the unit of illumination. So a 5W LED torch produces700 Lumens, if focused onto a 10 SQM area will give you 70 Lux. Bright enough for country lanes.

So, the two bikes I mentioned, one 20 lux and the other 180 lumens, are both gonna be pretty poor then?

 

[soundwave]

So, the two bikes I mentioned, one 20 lux and the other 180 lumens, are both gonna be pretty poor then?

yup you want as many lm you can afford esp if no other lighting why that 8000lm magic shine light is about the best bang for ur bucks.

https://www.lupine-shop.com/de/led-lampensets/alpha/

https://exposurelights.com/?SID=t8jlcqqmtehi0neivg5dr56ag3

 

[Laser Man]

I'd expect a whole bike for the price of that Lupine light!

 

[anotherkiwi]

So, the two bikes I mentioned, one 20 lux and the other 180 lumens, are both gonna be pretty poor then?

Yes, they are within the legal limit however.

As Woosh says above 70 lux is about right for a pedelec in rural areas. I loved my 80 lux light while it worked - the 10 extra lux made a world of difference. Second point is beam shape, you want those lux to be at the right spot on the road ahead of you. b+m do very nice beam shapes. Also out there in the country you want oncoming motorists to see you but you don't want to blind them, beam shape very important there as well.

Now I ride a trike so I am looking at 150 lux lights

 

[Andy-Mat]

So, I'm in the process of choosing my first e bike, and one thing that's very important to me is good lights, as I live in the middle of nowhere, (no street lights, or ambient lighting from houses etc.). There are a couple of Cube models I'm weighing up, but one's front light is described as 20 lux, the other as 180 lumens. Which would be better?
Is there actually any way to tell, other than seeing them both in action?

I see where you are coming from, but I personally do something different as my first e-bike, when the battery was empty (it will happen to you!), it shut off everything, so night and no lights!!
So I simply bought extra lights, with their own batteries, added them to the handlebars and under the saddle, and then I could use them all together if I wished, but I always have light! Spare batteries for a long ride go in my pocket, butI have never ever used them yet!!
The rear light I have also has a loud alarm with a remote control (cheap on ebay), to let me know someone is fiddling with the security chain, its very sensitive.....
Also, it is not obvious, as its mounted under the saddle, that it is also an alarm.
I hope this helps you to invest in a good bike and not to worry about the lighting too much....
regards
Andy

 

[Fishy]

I see where you are coming from, but I personally do something different as my first e-bike, when the battery was empty (it will happen to you!), it shut off everything, so night and no lights!!
So I simply bought extra lights, with their own batteries, added them to the handlebars and under the saddle, and then I could use them all together if I wished, but I always have light! Spare batteries for a long ride go in my pocket, butI have never ever used them yet!!
The rear light I have also has a loud alarm with a remote control (cheap on ebay), to let me know someone is fiddling with the security chain, its very sensitive.....
Also, it is not obvious, as its mounted under the saddle, that it is also an alarm.
I hope this helps you to invest in a good bike and not to worry about the lighting too much....
regards
Andy

Yea, thanks. I certainly wouldn't choose a bike based on which has the best lights, I was more trying to understand the relationship between Lux and Lumens, and get a handle on what the equivalent light would be on the two different ratings (if that makes sense) . Like you said, I'll probably add some more anyway.

 

[Fat Rat]

Quote ......

"Lumens is how bright a light source is and lux is how much light lands on a surface."

Yes, but without giving a distance, surely a lux rating is meaningless?
20 lux at 1mtr, is going to be completely different to 20 lux at 10mtrs, or have I got that wrong

Your right
a lot of companies measure lumens at source
and a lot as already mentioned guess and add more to make there cheap lights look impressive on paper
for instance a t6 emitter can't deliver any more than a 1000 lumens at 3.2a at source that is also with efficient cooling so a lot of figures quoted on the likes of eBay etc are con artist's just trying to sells lights to people who don't know any better
True big lumen lights with useable continuous reliable power are costly in general for a reason
Just don't get to hung up on lumens figures either it also has a lot to do with the quality of the electronics and reflector device also which donates how much useable light you get on the road in front of you
Within reason you do pay for what you get with lighting

 

[RossG]

I've got a rear light on one of my bikes that throws laser beams down onto the road. Probably highly illegal, looks good though.

 

[sjpt]

I've often thought a side light projecting the indicate minimum safe passing distance could be useful.

 

[flecc]

I've often thought a side light projecting the indicate minimum safe passing distance could be useful.

The highway code indicates one and a half metres. I think a light stuck out that far might cause the odd problem!
.

 

[vfr400]

I've got a rear light on one of my bikes that throws laser beams down onto the road. Probably highly illegal, looks good though.

I've noticed that motor vehicles treat you with much more respect when you use those laser beams. I don’t know whether it confuses them, its the width on the road, or what.

 

[RossG]

Maybe it puts the fear of god in them. Just imagine using a laser rear light in foggy weather, it would look like an alien spacecraft about to set down.