Lights-Lumens, Lux, Watts, Candlepower...HELP!

[Milfred Cubicle]

Does anyone know of a simple way of finding out the relative power of bike lights? I'm in the market for a new commuting/audax light, and am baffled by all the various rating. I don't want a light with a seperate battery pack, so that rules out most of the super high powered stuff. I've narrowed it down to;

A HOPE single l.e.d. (240 lumens) £75

Cateye E.L. 530 (1500 candlepower) £40

Smart 35 lux £45

If anyone has any experience of any of these models, I'd love to hear any opinions. Or if anyone has some SIMPLE equations for working out the ratings,I'd appreciate it. Thanks.

[NUKe]

I use Cateye 530 I commute on unlit roads and its easy to see up 20 meters in front. not the brightest light onthe market, but one of the best in its price bracket and excellent battery life, does at least a week of commuting before I recharge the batteries~ 6~9 hours on full beam, using NiMH rechargables
. Was best in class when it was released a couple of years ago, but Cateye have better ones now as well although more expensvie Cateye EL600 and 610 are brighter but have shorter run times.

[robwa10]

I asked a similar question on here last winter. Unfortunately there are no simple (or even difficult) equations for working it out. It seems to be a good way to keep people from comparing your companies light to another companies. Not sure about the particular models you mention but here's a link to Peter White's site were he reviews various lights.
http://www.peterwhitecycles.com/headlights.asp

[gilesjuk]

Anything over 180 lumens or over will be fine for dark conditions on the road.

If you're hurtling through the woods on a mountain bike however you may want something 400 or above, one in the bike, one on your head.

What you will find out is that some lights have a high number of lumens but a narrow beam. The wider the beam the more powerful the light source needs to be.

[PW]

Hope do one with 4 leds, I met one on the towpath one night and it's seriously bright.
If the Ixon IQ is anywhere near the dynamo powered IQ Cyo for brightness and beam length then that should be worth looking at.

[Manx Cat]

Hi MC

I have just purchased a Hope lamp. Its 240 lumens, with a rechargeable battery. Battery takes just 3 hours to fill!

I am VERY pleased with it. I used to have a vega by Light and motion (about 120 lumens on high beam), but I purchased this lamp twice and both lamps died just after a year of use. At £100 a pop this was a bit pricey. When the battery dies the entire lamp has to be chucked out, but wiht the Hope lamp, you can get replacement batteries and even take a spare with you if needed. They are nice wee tiny batteries too, and strap nicely on the stem of my bike.

Only slight disadvantage of the Hope is that 240 lumens isnt quite enough for the mtb, but its more than enough for the commute, I have not as yet used full beam.

It has 5 different settings,, and I find the highest setting too high for the commute setting 4 leaves a nice swath of light across the entire road, not just on my side of the road. I have to cycle 3 miles out of my commute in total darkness in the countryside. Another good thing about Hope is that I purchased this from my LBS and they told me they get the very best after sales service of any make that they stock with Hope. Now that is a very good recommendation in my book.


My LBS said they (Hope) have a 'borrow' service at your LBS if they stock them. So you can try before you buy.


Mary

[Milfred Cubicle]

Thanks folks. All really useful. The Link to Peter White's site was great.
Erring towards the Hope light. I've used their kit for years, and it's never failed me.

[Alastair K]

I've got the Hope Vision One (240 lumens) and can't recommend it enough. Good beam, well made, and with a decent set of rechargeables it'll last 3 hours.
Off road I use it on the bars, with a DiNotte 200 lumen on the helmet and I'm more than happy on unknown tracks.

Bracket is easy to swap between bikes (easy to steal??) but needs a couple of layers of insulation tape around the bars to stop the lamp slipping on rocky downhills. If it died I'd buy another one tomorrow.

[andrew_s]

Watts are a measure of the power consumption of the light.
Lumens are "amount" of light - effectively also power, but after the conversion into light. It's the same regardless of how the light is focussed.
Candlepower (or candela) is beam intensity (lumens per solid angle). If you focus the light into a narrower beam, the candlepower rating increases.
Lux is surface illumination (lumens per square metre). As well as getting a higher rating for a narrower beam, you also get a higher rating if the light is closer to the surface you are shining it on.

The only convertible units are lux and candelas, but you have to know how far away the surface used to measure the lux was. It's usually 10m, because that's how German road lighting regulations specify required lighting power, but I have seen 1m lux quoted too. At 1m, 1 lux = 1 candela. At 10m, 1 lux = 100 candela.
For converting between watts and lumens, you have to know exactly what the light source is. An old style bulb may give only 10 lumens per watt, but the best LEDs can give 120 lumens per watt when run at a reduced power.

You have to watch out for lights that claim a high candlepower or lux rating by concentrating all of the light into a very narrow beam. The Cateye EL530 is like this.
You also have to watch for "manufacturers rating" on the amount of lumens from an LED. Lumens aren't easy to actually measure as you have to add up the brightness of all parts of the beam. Instead, many makers just quote what the LED manufacturer says it will do, and ignore losses in the lens/reflector, reduced output due to the LED getting hot etc.
The other thing you have to watch for is the mismatch between quoted powers and quoted runtimes. A 2500mAh AA NiMh battery has 1.2V x 2.5Ah = 3 watt-hours of energy in it. If a light has 4xAA, claims 3W and a 10 hour runtime, it's not true, as 4 AAs will only run 3 watts for a maximum of 4 hours. It's probably 3W with new batteries, then gets progressively dimmer.

For road riding at reasonable speed (20mph) on unlit country roads, you want about 100 lumens in a fairly narrow beam (but not as narrow as the EL530).
It's nice to have more available for faster downhills.

For battery lights, I'd go for either the Hope or the B+M Ixon IQ.
The Hope is brighter, but actually puts less light on the road because the beam isn't so well controlled.
The Hope has a foible that you may not like, in that when the batteries can't cope with the current power setting, it turns itself off. You can turn it right back on at a lower setting (provided you didn't crash first ).
The B+M comes with a set of AA and a charger
The B+M is currently out of stock at dotbike, who are the cheapest UK source (I believe). Also check Germany - eg here, no charger/batts

[rualexander]

I got my Ixon IQ from Bike 24 in Germany:
http://www.bike24.com/1.php?content=8;n ... 7b411812af

Superb light!

[insanityideas]

My local bike shop has a "wall-o-lights" where you can try out the lights and get an idea of brightness and functionality. Its great for discovering that some lights have tricky controls, obviously difficult to judge effectiveness in a well lit shop, but you can at least compare one light to the other using a sheet of paper to judge the beam. Looking right at them can damage your eyes tho.

They have cheepo lights as well as the multi £100 lights.

I make my own because I know enough about electronics to know how cheap and easy to use the parts are, and don't mind a bit of Heath-Robinson about my bike kit.

[Tonyf33]

I've been using one of these for the last 2.5 years, http://www.parker-international.co.uk/1 ... n=pid11088
Personally I'd say don't get the Cateye, it's overpriced & not all that great for what you are paying. I've had both the Cateye EL-500 & 530 and I think the Raleigh light is better in every way and at the price you could buy 2 of these for the price of the Cateye & buy yourself some decent rechargeables.
I find mine invaluable when in heavy traffic during the day and at night on lit roads it is more than adequate. A single one is just about useable on roads without lighting if you've got good eyesight & dont go too fast otherwise I'd say this is a perfect light for others to see you with.
As the casing is metal it doesn't break when you drop it like the Cateye ones do (DOH!) & slim/light enough too be used as a hand held torch. Takes 4xAAA & lasts for about 20-25 hours

The Hope light is superb and is very much useable on unlit roads, however you'd need to buy top quality rechargeables like the Ansmann 2850/3000mAh AA's or it wont work properly, you only get 3 hours run time too. Factor in the cost and for your typical useage I'd say it's overkill.

At the end of the day, try out some lights in a store if possible but I'd definately recommend the Raleigh light.

[rualexander]

The Hope light is superb and is very much useable on unlit roads, however you'd need to buy top quality rechargeables like the Ansmann 2850/3000mAh AA's or it wont work properly, you only get 3 hours run time too. Factor in the cost and for your typical useage I'd say it's overkill.

Why won't it work properly?

[Tonyf33]

The Hope light is superb and is very much useable on unlit roads, however you'd need to buy top quality rechargeables like the Ansmann 2850/3000mAh AA's or it wont work properly, you only get 3 hours run time too. Factor in the cost and for your typical useage I'd say it's overkill.

Why won't it work properly?

SJS says 2850 minimum power & Wiggle say lower powered batteries could be an issue, looks like the power consumption of the Hope means that not all rechargeables will be able to supply enough power to the light.
Given you can now buy an Ansmann fast charger with 4xAA 2700mAh batteries included for £10 It's not overly expensive to get really top quality AA's anymore

[Graham]

I make my own because I know enough about electronics to know how cheap and easy to use the parts are, and don't mind a bit of Heath-Robinson about my bike kit.

Have there been any significant improvements in cost/performance of the components in the last year ??
I didn't get round to building a front light last year - mainly due to the confusing number of options available.
Hopefully I can sit down a study my way through the maze during the long nights this winter.