Commuting - Lighting Question

How long after sunset can a cyclist reasonably rely on twilight to see where he is going.

If it's not broad daylight, I run a light and two blinkies to be seen, but my headlight is fairly inexpensive cateye EL-300 that is less than stellar for seeing on a really dark road.

My commute is flat, straight and wide on a decent road. But portions of it are rather dark. Basically, I need to see well enough to spot things that might have been left in my path like car parts or dishwahers.

It takes me about 50 minutes. The darkest part is near the end -- the Yolo causway and along I-80.

Being a teacher, I've just been making sure I'm on my way home by 4:00. If I needed to stay until 5:00, would I have any problems?

Keep in mind, twilight/dawn is the most dangerous time of the day to drive. At those times, you need lights to be seen even if you don't need them to see by. The sun glare can kill you.

How long after sunset can a cyclist reasonably rely on twilight to see where he is going.

If it's not broad daylight, I run a light and two blinkies to be seen, but my headlight is fairly inexpensive cateye EL-300 that is less than stellar for seeing on a really dark road.

My commute is flat, straight and wide on a decent road. But portions of it are rather dark. Basically, I need to see well enough to spot things that might have been left in my path like car parts or dishwahers.

It takes me about 50 minutes. The darkest part is near the end -- the Yolo causway and along I-80.

Being a teacher, I've just been making sure I'm on my way home by 4:00. If I needed to stay until 5:00, would I have any problems?

I love the Light & Motion Vega that I got this year. I have it mounted on a swing-grip alongside a Cateye EL-500. The Vega gives me plenty of light even when I am riding on a very dark parkway, for up to 18-20mph. It also has a flashing mode that is very useful in low light conditions, like dawn and dusk, for being 'seen'. I like having two lights, just in case one goes on the fritz.

How long after sunset can a cyclist reasonably rely on twilight to see where he is going.

If it's not broad daylight, I run a light and two blinkies to be seen, but my headlight is fairly inexpensive cateye EL-300 that is less than stellar for seeing on a really dark road.

My commute is flat, straight and wide on a decent road. But portions of it are rather dark. Basically, I need to see well enough to spot things that might have been left in my path like car parts or dishwahers.

It takes me about 50 minutes. The darkest part is near the end -- the Yolo causway and along I-80.

Being a teacher, I've just been making sure I'm on my way home by 4:00. If I needed to stay until 5:00, would I have any problems?

Why do you not need to see smaller things that can give you a flat? What kind of tires are you on? I don't quite understand.

You need Cateye's best tailight. No ifs and or buts. And you should have a decent headlight.
This is what I have and I think of it as a minimum for your type of commuting. I have one, and I am thinking of getting a second. Or breaking down and getting one of the super expensive ones.
http://www.nashbar.com/profile.cfm?category=101&subcategory=1067&brand=&sku=3865&storetype=&estoreid=&pagename=

Tailight
http://www.nashbar.com/profile.cfm?category=101&subcategory=1068&brand=&sku=12860&storetype=&estoreid=&pagename=
Carry spare batteries for your tailight, I bet this baby chews 'em up.

You did not say how much you were willing to spend. There are several ways to light up your world. The way I did it was by getting a 13 watt Cygolite Metro that has dual 6.5 watt beams and runs on 6 D batteries which I happened to like that, and the cost of the light was only $48 and is significantly brighter then any LED light on the market except for maybe the new Cateye TripleShot that cost over $300. Next I added a front Xenon amber flasher for $15 to grab the attention of motorist who fail to recognize the small bike headlights. Next I got the Cateye LD600 tailight for $18 which was the brightest taillight at the the time but now they have the LD1000 which is probably twice as bright as mine, but the 600 is blindly bright and when mounted vertically can be seen from at least 45 degrees off axis. Next I added those little barend taillights for $15 which are also very bright and can be seen from 45 degrees off axis. I also use leg band reflectors and reflective tape on my helmet and on my seat bag and jacket. My whole lighting system cost about $100 and I have had comments from motorist as to how well they could see me even from a distance.

Or you can go with a brighter front light if needed but these can cost more money. Cygolite has a 25 watt dual beam rechargeable bottle battery type that cost around $90. Regardless you should still get a front flasher.

Also I read somewhere where the Cateye Micro-Halogen light when used in pairs, one on each fork, is as bright as a 6 watt light. I did see a test that did show the Micro Halogen to be brighter then any LED light currently on the market except for that Tripleshot maybe. The Micro halogen is a self contained 4AA battery type of light. I did know of a person who was touring and actually had put put those on his fork (1 on each blade) and on his helmet along with a hub generator light system. But again you should use a front flasher.

Thanks for your replies. However, my question was not so much about what light to get -- I just bought my EL300 and I'm sort of stuck with it. Rather, it was about what time to leave work, given the light that I have.

The EL300 is great for being seen. However, if I'm on a dark road a half an hour after sunset, do I need the really expensive setups that cost over $100?

$100 isn't what I'd call "really expensive." :) Try this on for size: http://www.gretnabikes.com/product.asp?product_ind=69&cat_ind=7 What I suggested in your other thread on this topic is a $120-ish NiteRider 15W single-beam that would last many years. Go to this page (http://eddys.com/site/page.cfm?PageID=493) and click the EL300 to see its beam pattern, then click the NiteRider Digital Evolution (which is another 15-watt NiteRider). Which one is going to show a dark chunk of rock in your path with several seconds of reaction time to spare? Eh? ;) Hey, they're your teeth, skull, skin, wheels and tires at stake...

Anyway, we cannot advise you on what time to leave work, because sunset doesn't occur at the same time every day, and we can't get inside your eyeballs, so use your common sense and judgement. But if you buy the NiteRider, I doubt you'll regret it. I use my high-powered headlights even in the daytime to help keep my visibility level up in traffic.

The "seeing" also depends on the phase of the moon. In a full moon you really dont need lights to see the road.
I used to vary my commute to avoid twilight. I prefer darkness when my lights can be seen by cars much more easily.

Rather, it was about what time to leave work, given the light that I have

My general rule of thumb is 20 to 30 minutes before sunrise and after sunset. This value corresponds to "Civil Twilight" defined as


Civil twilight is defined to begin in the morning, and to end in the evening when the center of the Sun is geometrically 6 degrees below the horizon. This is the limit at which twilight illumination is sufficient, under good weather conditions, for terrestrial objects to be clearly distinguished; at the beginning of morning civil twilight, or end of evening civil twilight, the horizon is clearly defined and the brightest stars are visible under good atmospheric conditions in the absence of moonlight or other illumination. In the morning before the beginning of civil twilight and in the evening after the end of civil twilight, artificial illumination is normally required to carry on ordinary outdoor activities. Complete darkness, however, ends sometime prior to the beginning of morning civil twilight and begins sometime after the end of evening civil twilight.

Your actual experienced may vary dependent upon weather conditions and your own eyesight. Throw in what kind of roads you're riding and any artificial lighting.

I ride rural farm roads, I have better than 20/20 vision (and oddly enough complete color blindness) so the civil twilight point works well for me. Then again, I now ride with both a dual helmet (http://home.socal.rr.com/laseredge/dvd_001.jpg) and handlebar (http://www.bicyclelights.com/OldSite/images/L1.jpg) system. Plus the usual menagerie of blinkies. SO now I enjoy rolling out in complete darkness.

I generate sunrise / sunset data here: http://aa.usno.navy.mil/data/docs/RS_OneYear.html

Thanks for your replies. However, my question was not so much about what light to get -- I just bought my EL300 and I'm sort of stuck with it. Rather, it was about what time to leave work, given the light that I have.

The EL300 is great for being seen. However, if I'm on a dark road a half an hour after sunset, do I need the really expensive setups that cost over $100?
You can probably see where you're going just fine half an hour after sunset as long as you don't ride very fast. This also depends on conditions. You can see where you're going just fine all night long if it's clear, there's a full moon, and you're not under a tree canopy.

But "need" is relative. I put a good chunck of my cycling budget into lighting and other safety gear (like good glasses). I think it's far more important than, say, an Ultegra drive train upgrade or the $140 Brooks saddle I've been drooling over.

I generate sunrise / sunset data here: http://aa.usno.navy.mil/data/docs/RS_OneYear.html

When you use this utility, instead of generating sunrise and sunset times, generate the civil twilight times. Civil Twilight is before sunrise/after sunset and generally marks the point at which the light level is too low to see well without lights. Of course, local cloud cover may affect these times.

. . .I generate sunrise / sunset data here: http://aa.usno.navy.mil/data/docs/RS_OneYear.html


When you use this utility, instead of generating sunrise and sunset times, generate the civil twilight times. Civil Twilight is before sunrise/after sunset and generally marks the point at which the light level is too low to see well without lights. Of course, local cloud cover may affect these times.
This is a very helpful site. Thanks.

Thanks for your replies. However, my question was not so much about what light to get -- I just bought my EL300 and I'm sort of stuck with it. Rather, it was about what time to leave work, given the light that I have.

The EL300 is great for being seen. However, if I'm on a dark road a half an hour after sunset, do I need the really expensive setups that cost over $100?

There are a number of things you can do to get a light for less than $100. Nashbar (http://www.nashbar.com/results.cfm?subcategory=1067&category=101&browse=&storetype=&estoreid=&brand=&searchbox=&start=1&orderby=price1&pagename=) sells a number of lights that use MR11 bulbs for less than $50. Look at the Niterider NR50 for example. The NR50 is meant to be run on alkaline batteries at 6 V and it is a 7.2W bulb but you can replace the battery box with RC car batteries from Radio Shack (get a charger while you are at it) which will increase the brightness of the bulb by overvolting it. With a 7.2w bulb and a 7.2V 3 ahr battery you should be good for run times of nearly 3 hours. You can also get replacement bulbs in higher voltages from a number of places. http://www.batteryspace.com/ is one. At the price that Nashbar is selling these for you could get 2 (batteries are round $30 each) and put one on your helmet. Nothing makes seeing stuff on the side of the road easier than a helmet light.

Performances sells the Cygo (http://www.performancebike.com/shop/profile.cfm?SKU=17645&subcategory_ID=4320) for around $70. This is a complete system so you wouldn't have to futz around with connectors or wiring. I don't have any direct experience with Cygo but I've heard good things about them.

Nashbar also sells the Nitehawk emitter (http://www.nashbar.com/profile.cfm?category=101&subcategory=1067&brand=&sku=11793&storetype=&estoreid=&pagename=) which isn't as bright as the other systems but is brighter than the Cateye. It also has an incredible burn time. I used one this fall when it wasn't too dark and it worked well. The batteries lasted at least a month on the high burn rate.

Hope this helps.

Here are the definitions of different twilight conditions and short summary:

Civil twilight is defined to begin in the morning, and to end in the evening when the center of the Sun is geometrically 6 degrees below the horizon. This is the limit at which twilight illumination is sufficient, under good weather conditions, for terrestrial objects to be clearly distinguished; at the beginning of morning civil twilight, or end of evening civil twilight, the horizon is clearly defined and the brightest stars are visible under good atmospheric conditions in the absence of moonlight or other illumination. In the morning before the beginning of civil twilight and in the evening after the end of civil twilight, artificial illumination is normally required to carry on ordinary outdoor activities. Complete darkness, however, ends sometime prior to the beginning of morning civil twilight and begins sometime after the end of evening civil twilight.

Nautical twilight is defined to begin in the morning, and to end in the evening, when the center of the sun is geometrically 12 degrees below the horizon. At the beginning or end of nautical twilight, under good atmospheric conditions and in the absence of other illumination, general outlines of ground objects may be distinguishable, but detailed outdoor operations are not possible, and the horizon is indistinct.

Astronomical twilight is defined to begin in the morning, and to end in the evening when the center of the Sun is geometrically 18 degrees below the horizon. Before the beginning of astronomical twilight in the morning and after the end of astronomical twilight in the evening the Sun does not contribute to sky illumination; for a considerable interval after the beginning of morning twilight and before the end of evening twilight, sky illumination is so faint that it is practically imperceptible.

Go to http://www.sunrisesunset.com/ to get the Actual Twilight, i.e. sunrise/sunset times in your time zone for the month. Weather.com only gives sunrise/sunset times. wunderground gives the actual times for all 4 twilights for your zip code.

Get a good headlight. Is your life worth $100?

How long after sunset can a cyclist reasonably rely on twilight to see where he is going.


Not at all. In naval aviation (my previous career), it is considered to be "night" 30 minutes PRIOR to sunset. Twilight is the HARDEST time to see. Even a powerful light will not make it easier to see during twilight. If you are riding during the 1 hour surrounding sunset you should assume that your and everyone else's vision is significantly impaired.