Thinking of getting a 5-mode flashlight for my bicycle mostly for daytime riding in flashing mode. Seems like most flashlights run in high mode while flashing. A couple of questions:

1. What's the minimum lumens recommended for this purpose?

2. In flashing mode (high mode), how much longer will I be able to operate the battery before a recharge? The one I'm looking at has a runtime of 2 hours in high mode.

Lumen output is only one thing to consider. Apparent brightness also depends on the beam angle that the output is concentrated into. And a front light us only effective when riding against traffic. If traffic is approaching from the back then a bright front light is useless. That said - I've actually been very impressed with the performance of the Blackburn VOYAGER 2.0 FRONT LED light. In fact I run with two of those in flashing mode rather than a 700 lumen light also on the bike simply because run-times are better and I can't see any effective difference in the daytime. At $20 they're under-rated. They output a narrow beam that doesn't light the road effectively at night but will reach two blocks ahead and illuminate street signs. And daytime visibility is EXCELLENT!

I got 2 of these solely for flashing mode duties in both daylight and at night:
Rosewill RLFL-11002 3W 220 Lumen Cree LED Aluminum Flashlight w/ Bicycle Bracket

The bracket alone is worth the price of admission. The LEDs are not that great for illuminating the road ahead because of the lack of reflectors or lens but they are great as a "to be seen" light. The lights flash about 4 to 5 times a second.

As a cager, I find that obnoxious Fredly bright neon yellow jackets do wonders for visibility. I've seen riders way off down the road because of their large spot of yellow jacket than from their red rear blinky. Combine that with a blinking light.

I think flashing modes generally will run for 2x longer than steady modes. The light should tell you the run times. I would recommend a floody light for visibility. XM-L or P7 flashlight will do. shiningbeam.com has some nice lights, but none of them seem to have flashing modes. What battery or form factor are you interested in? The KD C8 is a popular inexpensive decent light that has strobe mode. And it's perfect for night use. The Magicshines also have strobe mode. There are lots of MS and MS clones out there. You could purchase an older P7 version pretty cheap.

A light with an XP-G emitter driven at one amp on an 18650 will run over 5 hours on strobe.

Excuse my ignorance, are "floody lights" the same thing as a "thrower"?

The flashlight I've been looking at is this one with 1,200 lumens. It gets very high positive reviews. A reviewer, however, said the following:

Evidently, this light is not a thrower. If you're looking for one of those...look elsewhere. It throws usable light a little past 100 meters. If you need something that'll throw light out to 300 meters, look for something with a larger reflector or a smaller emitter.

This quote made me question whether this flashlight will be good for road cycling. I basically want to get away with a good and inexpensive flashlight that will be quite visible for daytime riding in flashing mode. I also want to place it permanently under a randonneur rack without having cables or external battery packs. I remember reading somewhere that you have to increase lumens considerably to be visible under the sun, even in flashing mode. By the way, I do wear my green fluorescent safety vest, but a good flashing light won't hurt. My rides last 3-4 hours and I don't mind switching batteries if necessary. I guess a couple of rechargeable 18650 batteries should be plenty. If I ever use it at night, it will most likely be in low or medium mode so it won't be so annoying.

What do you guys think?

Almost all XM-L lights have a good combination between flood and throw to make them excellent bike lights. They have bright hotspot with good spill. If you look at the beamshots of this light, you should be able to see the difference. The very narrow beam is all throw. It will light up a small spot at a great distance. The wider beamshot doesn't look as bright because the light is is spread out over a wider angle. The P7 based lights have quite a bit wider beam than XM-L. The P7 wasted usable light at wider angles where it isn't useful to a bike rider.

That flashlight you linked to is typical of the XM-L lights. I can't comment on that specific light, other than to say it won't be 1200 lumens. Those Chinese lights all lie about the specs; if you are lucky, it will be 700 lumens. It's a crap shoot. You can read about all the cheapest lights over at budgetlightforum.com. The KD C8 has a lot of fans and is a known quantity; it will be similar to the DX light. I can get 1.5 hours on my KD C8 on high. I always have a spare battery in my seat pack.

Personally I think it'll be fine. Not every reviewer is evaluating things as a potential bike light. A speed of 15mph is only 22 ft/sec. How far ahead does anyone need to light up a road at that speed?

And visibility is relative. A 'flood' will also be more visible over a wider angle to oncoming traffic, simply because the light source will be less focused. That actually provides better day-time visibility and night-time visibility thats OK for a cyclist. Lights are usually a supplement to street lighting and unless you're in an unlit area, are more critical to being seen than for lighting up the road.

Thank you, everyone! I'm going to go ahead and order that flashlight.

I'm glad you read something that helped with your decision. I read mostly about nighttime visibility and non-relevant opinion. One poster said a narrow beam is excellent for daytime visibility, then later the same person says a broad beam is better. I would like to read an objective report if you could take the time for an update on your experience. Have someone watch your bike at a distance, top of the hill, bottom of the hill, while in a corner, etc., and share the feedback. Bike movements are too dynamic to rely upon straight-on evaluations. Lately I've spent time at a large city MUP observing bicycle lights at day & dusk and poor off-axis visibility was apparent.

Gee - if you were referring to my initial recommendation about that Blackburn unit - that's a design that uses THREE LEDs across a curved front panel with individual lenses designed to make the light more visible from the sides in spite of the narrow beam. Not all these things have identical designs and the OP subsequently asked some specific questions about one light in particular that uses a single LED. My apologies if that wasn't quite spelt out clearly enough for you.

Will do! It will be some time in May. I'm making a trip to the U.S. in April to pick up this and some other items.

Chris, I am right there with you.. First, I started with the really small Chinese flashlights. However, I was so impressed on how much light the $4.00 Chinese flashlights dished out, I went berzerk and ordered me a few so-called 1300 lum, and a couple 1600 lum babies.. they be running off 18650 and 26650 3.7 rechargables..

Also, I found out that running the flashlights in pairs looks cool.. Gives balance to the bike's looks and at the same time giving more light up front..

The LIGHT POLICE are going to get my butt for sure!!

That's fine if you are keeping your eyes on the road all the time, but when there is traffic, I might look away for a couple of seconds, or look behind me. I don't want to look back on the road to find that I have to make a quick stop or maneuver around something in the road.

Personally I think that narrow beams give poor coverage but since you feel so strongly about those lights, maybe you'd be good enough to post some beamshots taken with your $20 flashlights and demonstrate exactly how they give better coverage than the ones I've already posted beam shots using P7's? If you decide to do that, can I ask you to also use the same camera settings so we at least have a reasonable point of reference? Maybe I wasted a lotta money

Narrow beams do give poor coverage. XP-G isn't as narrow as XP-E or XR-E (IIRC). And I ride with two lights: floody on the bar, throwy on the helmet so that I can direct it at any angle. I really like it on the dark MUP at night where there are cats, mice and skunks sitting on the side of the path where they are harder to see.

I'll have to figure out how to use manual settings on my camera, but I'll try to get some beamshots that are honest.

Post the make and model of your camera and I'll tell you how to set it up. Agree a combination of helmet and bar lighting works best and look forward to seeing your shots. And now before we completely derail this thread, lets keep in mind that the OP's original concern was for a light for day-time riding.