How many lumens does one need?

[Shut Up Legs]

Car headlights have a "shaped beam", that allows brightness, but because the beam has no "top half" it does not blind in the same way that a bicycle light with a full round beam and the same intensity will do.

Except when idiots insist on using high-beam as the default, and only switch to low occasionally, or the lights are mounted high (e.g. 4WD), or the lights just aren't adjusted properly and even low beam is pointed too high.

 

[Trull]

The brightness is only 20% of the real problem in real life…
For me the lighting problem is only solved when:
1) The beam is shaped to get all the light on the road with the road close to me being as bright as that far away (this is a selling point for the likes of B+M)
2) Proper bracket which does not rely on poxy rubber bands to work. These always break and always slip at 50k+ downhill…
3) Batteries are a pain - although I appreciate USB charging at work is great, when you remember.
4) Glare to avoid me losing my nightsight is controlled
5) Rattles are minimised so that you can enjoy the night

There's umpteen compromises to be made here, but my nicest setup is a B+M Cyo N Plus mounted on a fork crown steel bracket running off a Dynohub (Shimano as it happens - but any of the decent ones are just fine), backed up by a Lezyne Macro Drive and also a fleabay Cree XM-L with an added freznel lens so the beam was widened and not so glaring for oncoming traffic.

 

[PeteXXX]

Am I right in thinking that lux is a better measure of a lights usefulness? Like bhp on a car, more isn't always better, it's how the power is channeled.

 

[DrLex]

It's not just the number of lumens, it's the beam shape which determines where those lumens go. I often run a Magicshine MJ838 with a Philips Saferide 80. [...]

I gave my MagicShine away to a friend after getting a SafeRide; preferring the latter, I bought the dynamo version to use on another bike. I assume that companies like Hope and Exposure don't do units with shaped beams, as they sell to both the off-road and on-road market and the key selling points are lumens and run-time.

 

[Trull]

Yes PeteXXX, and its how the light is put out - does the lens channel less light nearest you and most into the distance? Does the shape of the beam avoid glare, but put most light where its needed? Is there glare back which can dazzle you? The German lights seem to do well in answering these questions.

 

[CopperBrompton]

As others have said, the shape of the reflector makes a huge difference. German lights are required by law to have properly-shaped reflectors, which is why B&M lights way out-perform their raw power.

 

[Stephen C]

I have the same Macro front/Micro rear combination, used it for 2 winters of a mix of town and country riding without any trouble. The Macro is more than enough to go at 20mph+ along unlit lanes, but I only used road that I knew well and knew where all the potholes were, I wouldn't be as confident along unknown roads. The Micro rear is a bit too direct for a rear light, I got a few comments about it being a bit too dazzling when riding through towns.

 

[400bhp]

Car headlights have a "shaped beam", that allows brightness, but because the beam has no "top half" it does not blind in the same way that a bicycle light with a full round beam and the same intensity will do.

Could someone tell this to Mercedes. I've noticed lately that on their newer cars the dipped beam is more like full beam.

 

[ufkacbln]

I think that part of the problem is the tendency to strips of LEDs rather than bulbs.

These are not focussed or filtered. Basically becoming more like the unfettered beams of bicycles

 

[the_mikey]

I carry two 500 lumen lights, rarely do I ever use both at the same time, mostly I use one on low power setting but occasionally there is a need to use both on high power to see my way through some of the unlit lanes around here.

 

[slowmotion]

This link is a bit old but it's a good introduction to the beam pattern issue that @McWobble flagged. I have never had any luck with spectacularly bright ebay general-purpose torches. They all went mad within two weeks, swapping between flash patterns at their own random pace.
http://www.torchythebatteryboy.com/

 

[HovR]

This link is a bit old but it's a good introduction to the beam pattern issue that @McWobble flagged. I have never had any luck with spectacularly bright ebay general-purpose torches. They all went mad within two weeks, swapping between flash patterns at their own random pace.
http://www.torchythebatteryboy.com/

I've had some good luck with the eBay general purposes torches, but I also know some people who have had issues with random mode changing, light won't stay on etc. In all of the examples I've seen the actual circuit boards and driver are fine, the bits that hold the internals were just loose, causing a bad connection (they're often never tight from the factory).

Grab a poking tool (the technical term, obviously) and tighten it up where the pin-spanner should go, unless you have an actual pin spanner, of course. It wouldn't hurt to add a bit of grease or copper-slip to the threads whilst you're at it, either. On one occasion I found the main switch was loose, but it was easy enough to solder back on.

They're pretty simple devices, really. I would advise to stay away from the lights that have zoom focus, however.

 

[Crankarm]

And what ever light you end up getting …………….. DON'T use it on the flashing or strobe setting .

Me, I have 3,200 lumens of light should I need it. Night becomes day. But no flashing unless I am flashed at then the strobe goes on which they don't like ……………..

 

[ufkacbln]

I use a Dinnotte rear light on flash, as backup to an RVLR compliant Cateye

Nipped down to the pub one evening when I was berated at the bar by a woman about how I was going to kill someone by causing a driver to have a fit using flashing lights!

When she was finished I asked two questions?

1. Was she aware that cycle lights are outside the trigger limits for epileptic fits, and according to the British Epilepsy Association there are no recorded incidents of fits triggered by bicycle lights

2. Was it this fear of flashing lights that had stopped her using her indicators coming off the roundabout and also when she turned into the pub car park?

She stormed off.....

 

[BigAl68]

And what ever light you end up getting …………….. DON'T use it on the flashing or strobe setting .

Me, I have 3,200 lumens of light should I need it. Night becomes day. But no flashing unless I am flashed at then the strobe goes on which they don't like ……………..

The flashers are already out round here... it really makes me angry especially the the Cree brigade who think they need to light up the cycle path like day and then have a second one on strobe. It is only mid august so by the middle of October I will have shouted "sort your lights out" at all of them more times than I should really need to.