Thorn Cycles Forum

Technical => Lighting and Electronics => Topic started by: Pavel on September 01, 2016, 04:49:43 PM

Title: Is two better than one?
Post by: Pavel on September 01, 2016, 04:49:43 PM
I wuz just wondering.  Does anyone run two dyno driven lights?  I find the only problem I have is that with a properly aimed light, as I get close enough to signs to read them with my fading abilities, the light no longer aims up high enough to read them.  The same sometimes goes for identifying features off to the side. 

So thinking about "ultimate" I wonder if there could be some kind of dual light rig, where one is on as per normal and the other, higher up on the bike somewhere, aimed much higher and switched on/off with a handlebar rocker switch.  Also, while the modern led lights, with their capacitors do a decent job in staying on a while when stopped, they fade so much in that state that I'm considering running that lights through some kind of battery, so that they stay at full brightness while stopped a while.

Has anyone walked (cycled)  down this path, and have any ideas and advice?
Title: Re: Is two better than one?
Post by: Andre Jute on September 01, 2016, 08:02:02 PM
I've long said that the German standard lamps are specified, by a bunch of politicians, for the convenience of motorists, not cyclists, and one of the main exhibits is the inadequacy of BUMM lamps in sign-lighting. (The failure of BUMM lamps until recently to provide adequate or any side lighting was a matter of LED development and an engineering/design choice to concentrate what light was available straight ahead.) There's nothing you can do about the sign-lighting problem except run a second lamp. Dan very recently in the thread Matt started about Amsterdam gave a link to a Dutch dealer and designer of components (M-Engineering) who has extensive literature on running a second lamp off one dynamo. You can then aim the second lamp upwards and to the left to light signs. That would be a touring setup, whereas what follows is good for day/night rides.

I don't use a second dynamo lamp, even though I have plenty and the electrical knowledge and skills to handle the wiring. Instead I solve two problems with one hit of the hammer. BUMM lamps, all German lamps and lamps produced under the influence of the wretched German legislation (meaning Dutch lamps and most of the French), lack a flash mode because it is illegal in Germany. So I use a small Chinese military/police torch with a flash mode and two steady modes attached to the handlebar by a fishmouth with velcro. Normally, both day and night, this points downwards, only a few degress off perpendicular to the ground, and just causes a flash of light to the ground which also lights me up. It is enough of an attention getter without irritating anyone. When a driver is stupid with his lamps or his speed in a narrow lane, I warn him once by turning the lamp up on the velcro swivel to just below his window height. If he is still stupid, I give it to him in the eyes. Nobody has ever needed a second warning.

(http://des.gearbest.com/uploads/201301/heditor/201301071122573009.jpg)
Cree Q5 3-Mode 350 lumens 18650 LED Flashlight with Battery and Charger, about $12 from Gearbest.com; you need to provide your own fishmouth and velcro strip for mounting it to the handlebar

When I need to read a sign, dimly perceived in the inadequate uplighting of my BUMM Cyo, I turn the lamp upwards and switch to dim mode (the bright mode is so strong, it could blind oncoming drivers unnecessarily). When I've read the sign, I turn the lamp down and onto flash again. It isn't ideal, because you still miss overgrown or worn signs if the second lamp is on flash and turned downwards -- I once missed a stop sign and rode across a junction in front of an articulated truck, which was hairy -- but it is better than the BUMM lamp alone. Another thing that isn't ideal is that the 18650 3300mAh battery inside my secondary lamp needs to be charged after every ride because all that flash and beam power wipes the battery in a few hours. But if I keep it constantly on dim and aimed upwards for signs it lasts well enough for summer evening rides. I could of course just wire it into my SON hub dynamo, or indeed the battery on my bike for the motor, but my nighttime rides are never that long or so far from home that the stress of not being able to see everything I should see builds up to breaking point; in addition I now ride only on familiar roads and at night more so. (Of course I'm the first to admit that's not sound reasoning; as road safety statisticians will tell you, most accidents happen within five miles of home...)
Title: Re: Is two better than one?
Post by: mickeg on September 02, 2016, 12:22:26 AM
Quote from: pavel on September 01, 2016, 04:49:43 PM
I wuz just wondering.  Does anyone run two dyno driven lights? ...

Several years ago, SJS had a closeout price on some bottle generator Lumotec Oval LED lights.  I bought two.  They were unswitched (bottle generator lights don't have swiches) and as an experiment I ran the two in series.  I needed a higher minimum speed to get both lights up to usable light, but when riding a typical riding speeds I got twice the light I otherwise would have gotten.  I just left them plugged in and therefore they were always on when I rode.

The key here is running them in series, not parallel.

I no longer run that dual setup, I bought a better light with USB port built in (AXA Luxx 70 Plus) and now use that around home. 

For my Iceland trip I was concerned that the waterproofing of my AXA light was not very good, so I instead bought a Sinewave Revolution USB charger which has outstanding waterproofing and I brought an older Lumotec Oval LED light to use as the headlight.

If you try to run two lights, I recommend that they are the same model, as each light will have to use the same amperage as the other.  If one light wants to use more amps than the other, well it does not work that way.  And if you wanted to have a switch to switch one on and off while the other stays on, the switch would have to short out the circuit across one so no power goes through the second light but instead is just a bypass.  I hope this is clear.

I got the idea for dual lighting from Peter White. 
http://www.peterwhitecycles.com/dualsetupfork.htm
http://www.peterwhitecycles.com/light-mounts.php

I think Peter also discussed using two lights of different types, but I think two of the same model is the best idea because of the amperage issue.

I made the light bracket for the two lights out of a piece of steel strapping that I drilled and tapped for the two lights.
Title: Re: Is two better than one?
Post by: martinf on September 02, 2016, 05:55:55 AM
One word of caution when using two lamps on a two wheeler.

If they are mounted side by side with a gap, in the rear view mirror of a bus/truck they look like a car a long way off rather than a bike that is much closer.

Years ago when I was working in public transport I once started pulling my bus out from the stop into the path of a motorbike that way. He was doing about 60 mph in a 30 mph limit area so both of us were at fault, however we managed to avoid a crash.

So when I have two lamps I mount them spaced vertically instead of side by side. Same reasoning for rear lamps.

My two-wheeled bike trailer is fairly wide, so on that I have fitted two rear lamps mounted as far apart as possible. It also has two large triangular reflectors as specifically used on trailers in Europe. On a narrow trailer, I reckon it is better to fit a single rear light and one triangular reflector on the offside.
Title: Re: Is two better than one?
Post by: Jim_Mercury on September 04, 2016, 10:16:01 AM
Same thing happend to me. Reversing car out of driveway early winter morning. Saw two lights. Thought it was a car about quarter of a mile away, so plenty of time. Almost wiped out a cyclist. Lost him against back ground of orange street lights.
Strange optical illusion. :o
Title: Re: Is two better than one?
Post by: Pavel on September 05, 2016, 02:33:14 AM
intersting.  I was teaching a course on high performance driving in the mid 80's and one of the bits of training literature referred to that same phenomena - in regards to how animals miss-judge the distance of cars approaching.  It seems that experiments led to the conclusion that small mammals mistook headlights to be eyes.  The victims however offered no input, on the theory. :D
Title: Re: Is two better than one?
Post by: mickeg on September 05, 2016, 05:00:13 PM
Quote from: pavel on September 05, 2016, 02:33:14 AM
intersting.  I was teaching a course on high performance driving in the mid 80's and one of the bits of training literature referred to that same phenomena - in regards to how animals miss-judge the distance of cars approaching.  It seems that experiments led to the conclusion that small mammals mistook headlights to be eyes.  The victims however offered no input, on the theory. :D

So, which animals have eyes that are a meter and a half apart?

In the photo of mine (posted above) you can see that the two lamps in my setup were quite close, maybe only 2 cm of space between them.  I would not worry about that causing a safety hazard.  But I think it is most often done with the lights lower on the fork legs to highlight bumps in the road better.  If you were concerned, you certainly could mount one higher than the other.  There are lots of motorcycles and motorbikes that have two headlamps, I have not heard of anyone having a problem with them.
Title: Re: Is two better than one?
Post by: Pavel on September 05, 2016, 08:25:32 PM
Quote

So, which animals have eyes that are a meter and a half apart?


Those that have seen it, have never been heard from again! :D
Title: Re: Is two better than one?
Post by: martinf on September 05, 2016, 10:03:49 PM
Quote from: mickeg on September 05, 2016, 05:00:13 PM
In the photo of mine (posted above) you can see that the two lamps in my setup were quite close, maybe only 2 cm of space between them. I would not worry about that causing a safety hazard.

No idea how far apart the front lamps were in my motorbike/bus incident, at the speed he was doing the motorbike disappeared very quickly.

Not tried side-by side lamps, but I would expect that with the power of modern LEDS they would look like a single lamp if very closely spaced, except perhaps in a rear view mirror, which reduces light intensity quite significantly.   

On family bikes, as standard, I have one generator-type front lamp (40 to 80 lux B&M Cyo or the Schmidt SON equivalent), which seems good enough for my type of riding nearly all the time, the exception would be off-road night riding, when it is difficult to go fast enough to get sufficient light to see obstacles. For that I have a 40 lux B&M lamp that I can clip to the handlebars, close to the centreline, so more or less vertically spaced over the fixed front lamp.

On the back I have at minimum one generator-type B&M mudguard-mounted lamp, mounted fairly low down, but never obscured by luggage. On most of the bikes that have racks I have a second generator-type B&M rack-mounted lamp, mounted higher up, but visibility from an angle is less when carrying luggage (Thorn racks are better than most others in this respect, as they are longer). And I nearly always use an additional battery-operated Cateye LD-1100, mounted wherever I can find room, often on the seat post. So long as it isn't obscured by clothing or luggage, the latter is visible over an angle of more than 180°, with two LEDs pointing directly sideways on each side, so increases visibility significantly on roundabouts/road junctions.

So up to 3 lamps at the rear, all on the centreline.



Title: Re: Is two better than one?
Post by: mickeg on September 06, 2016, 12:16:56 AM
I have no idea who owns the bike on the right in the photo, I saw it locked up near where I used to work, took a photo.  That I think has more than adequate rear lighting.