ganchan

I know the common wisdom is probably "as many as possible," but my budget won't permit that. I don't ride at night so I don't need a flood-lamp up front, but I do need safety lighting for my daytime trips. I have a Bell Beacon helmet-mounted dual light, but the red light on it looks pretty feeble to me (and the Beacon itself sits awkwardly and somewhat uncomfortably on my helmet).

I'd like a white blinkie on my handlebars and a rear blinkie that I can clip onto the base of my helmet. But what minimum lumens rating, if any, do I need to observe? I've seen rear lights rated at 3 lumens or less, but I 'd think the sunlight would wash them out completely....

Homebrew01

There's a "Lighting & Electronics" forum that has lots of discussions.

headloss 

As is usually the case, the answer is, it depends...

I find that 300 lumen is sufficient to light a dark unlit rail trail in a pinch (although I prefer to have two, one helmet mounted); 300 is more than enough in a lit cityscape. It also seems like a good output for being seen. I wouldn't personally go lower unless I got a good deal on something, in which case, I don't know having not tried some hypothetical light.
I definitely wouldn't go back to something that doesn't even list lumen or lux, such as my old cateye that is only useful as a flashlight to see in my pannier at night.

My tail light is 2 Watt, a cygolite hotshot, and I like it a lot. I bought it during one of Amazon's Christmas deals last year for $20.

I also have a dynamo setup on one bike and I'd say that my 15lux floodlight gives me about the same visibility as a 300 lumen spotlight, albeit two completely different spreads/patterns.

TrojanHorse

Yeah, check out the electronics sub forum...

you have seen lights rated at 3 WATTS maybe, not 3 lumens.

rm -rf

Rear blinkies usually have a narrow bright beam, with some side spill light. So mounting them on a helmet, seat bag, or jersey doesn't aim them very well. Even extremely bright lights like the Hotshot 2W won't seem very bright if they are aimed up in the air or off to the side. If you can mount it to your seatpost or seat stay it will be way more effective.

Just about any front or rear blinky more than $10 will be bright enough when blinking to be noticed during the day. Well, maybe not so much at noon in the sun. But very good at catching driver's attention in the mornings and evenings or in mixed sun and shade conditions.

Jarrett2

One meeeeelion lumens...

spdracr39

The only problem I see with lights over 300 lumens is they tend to blind oncoming riders if you are riding on a path.

Elvo

It's not about the (quantity of) lumens, it's about how you use them.

fietsbob

Just to be seen in a well lit city?, or to see on the dark road at 25kph+ is a different thing ..

Some people seem to think they need as Many as they can find, escalating into a Lumens one-upmanship contest..

I have no Idea about Your Needs..

Electronics, Lighting, & Gadgets

NB: Wally World is not where the good stuff is sold.

Hypno Toad

I like the NiteRiderLumina 700 - NiteRider

Four settings:
1:30HR High- 700
3:00HR Med- 350
5:50HR Low- 200
18:00HR Walk- 40

I typically run the 40 lumin for daytime running lights as well as dawn and dusk. 200 is fine for city night riding (with street lights). 700 for dark suburban roads or trails in the dark. I will always dim the 700 setting for on-coming traffic (cars and bikes alike).

Deontologist

Get a "5000 lumen" light from eBay. One of those Cree lights. I purchased one for 25 dollars. That thing, on its highest setting, lights up an entire street at midnight. If you look straight into it you will be temporarily blinded. Even if you put your palm in front of the light and look at the light reflected off your palm, you will be a little bit blinded. A GREAT deal for 25 dollars. Still works and I've had it for a month and have been using it daily.

Make sure you actually buy one of those Cree lights that comes with a battery ... the batteries aren't your run of the mill AA batteries but rather a little brick that you probably can't find at the local store or something.

gregjones

It gets covered a lot in the Commuting forum as well.

I posted some pictures about side visibity in the Commuter forum this morning.

energyandair

Why do you need lighting during the day? The right clothing can be very effective.

I'm not saying you necessarily don't but without knowing where you are cycling and under what conditions, its hard to give advice.

Astrozombie

~400, funny though taillights don't really list lumens.......get one that's at least $30.

gregjones

I wasn't planing on using a front light on the road bike. But I haven't gone to the bigger town south of us that I haven't had a Ricky Racer pass a slower car, illegally crossing a double yellow line to do so. That puts them in my lane on a two lane highway, headed towards me at 60+ mph. I'm just waiting on a "be seen" head light that's ordered to arrive, not enough to ride with at night but only a couple of ounces and it might prevent an accident.

How do you know whether or not you will need a safety device anywhere?

krobinson103

I like two 300 lumen spots. one aimed high, the other low. Aim the beams so they make one pool of light on the road with two hot spots. If need be I can raise one higher but I avoid that unless I know there are no other bikes or cars as these things get rather blinidng if you look right at them.

hueyhoolihan

how many lumens does it take to screw in a lightbulb? *hint*: lumens are brighter than they appear to be.

corrado33

I have a Fenix BT10, which is 350 Lumens on it's highest setting. On a familiar road, it's perfectly fine, even in complete darkness. However, if for some reason you have to ride on a gravel path or unfamiliar territory, you're going to want more. I find that at dawn and dusk are the times when I want more lighting. If it's perfectly dark out, you can get by with less light because your eyes are dark adjusted. At dawn and dusk that is not the case.

I haven't increased my lighting (I plan to soon), but I think ~450-500 would be minimal for riding on unfamiliar, rough roads. It also depends on how fast you're going. (If you're flying down a huge unfamiliar downhill at dark, you're going to want more.) I personally plan on buying a Fenix BT 20 which is 750 lumens max, and use it in conjunction with my BT 10. Light is additive, so I'd effectively have 1100 lumens at my disposal. Therefore, if I NEED the light, I have it, but most days I'd probably just ride around with one light on. This is for my commuter by the way.

I've ridden through a few hard rainstorms where my little 350 lumen BT 10 had me almost running into huge white trailers... (I'm not joking, I missed the trailer by a few inches.) I wasn't even riding in the gutter, it was illegally parked here...

If possible, get shaped beams that put all/most of the light onto the path that you're riding on. Many of the huge multi thousand lumen claims may indeed put out that much light, but it's not shaped so you're losing >half of it to the sky/sides, not to mention blinding people.

bmcphx

Depends on your budget and how much time you need from your light. Keep in mind that the advertised lumens are on high, and run times will be the lowest. I have an old 500lu light that would only last a 2 hour rode on low, about 200lu and it was hardly worth using.

I recently bought a 3200 lumen which I can run on high for longer than 3 hours or at 1600lu for 12 hours. It was expensive but I am much more safely visible and I will never have to worry about battery life.

How many lumens do you need? Get the brightest light you can afford, and for the love of Pete, don't buy a light made by an accessory company. Get something by a light maker, like light & motion, niterider, exposure, etc. You will actually get a decent level of service should you have an issue and they are generally much better quality.