Dinotte Glare Reduction Hack…

14 12 2010


Dinotte 200L-AA with DIY 1/3rd vertical cut off...

Bike lights that shine as much light up into the sky and other people’s eyes as they do on the road are a problem.  The glare they produce is painfully blinding and potentially dangerous for everyone since you are making it hard for oncoming drivers and cyclists to see where they are going right when they are close to you.  Germany mandates that bike lights don’t do this so they have some great lights with focused optics that take the wasted/blinding light and push it down in the beam pattern so it’s shining way down at the road the furthest away from the bike.  This is handy since it adds light where needed most and doesn’t bother other MUP/road users as much.

Unfortunately North American light manufacturers don’t offer these types of focused bike lights.  I assumed Dinotte didn’t offer such a light because of the expense and hassle involved, but I was shocked to find out when they posted on a related thread on BROL that they don’t think there is a problem.  They even go so far as to say the German style focused lights might be unsafe because they don’t pump light out in every direction.  My initial reaction was what planet do they live on?  I get blinded by symmetrical unfocused bike lights every night ride and I have to cover or change the aim on my Dinottes every night ride to avoid blinding people.  German laws are there to enhance safety and if anything the Germans are hyper-safety conscious when it comes to cycling.  Given that many randonneurs sing the praises of the focused European lights after using them at high speeds on a variety of roads all night when extremely tired you have to wonder how dangerous they could be?


Various bike light patterns...


Have a look in the image above at the symmetrical Dinotte 600L light pattern compared to the Scmidt Edelux pattern.  The difference is dramatic.  Peter White has an excellent set of photos showing what various lights he sells look like when shone down the road.  His images are also very instructive.

So the obvious solution is if you have $$$ to spend on a new bike light get one of the European style focused lights that Peter White sells.  What about the existing lights you have that are still working fine, but you are tired of blinding people with?  Well I faced exactly that problem with my 2 Dinotte 200L-AA lights.  They work fine and are worth about $300 so I don’t want to throw them out.  The discussion on BROL got me thinking and I tried a DIY vertical cut off using electrical tape.  This blocked the upper part of the light beam.

In this video I did the following:

  • pushed a bike away from camera with stock Dinotte 200L-AA aimed as I normally would and had Planet Bike Superflash on back aimed normally
  • pushed same config back towards camera
  • replaced stock Dinotte with same model light [same battery pack] that had a electrical tape vertical cut off covering 1/3 of the top of the lens
  • replaced Superflash with Radbot 1000 on rear
  • pushed bike away from and back towards camera

What I see in the video is:

  • stock Dinotte is very bright in the camera with a lot of light pumped into the lens causing glare [easy to spot]
  • Planet Bike Superflash is very bright [easy to spot]
  • with 1/3 vertical cut off is easy to spot, but much less light at the camera
  • is extremely bright

This simulates riding on a MUP…something that I do every ride in Victoria and given the lack of daylight much of this riding is at night. With this DIY cutoff I can ride the MUP and the streets without blinding anyone, but still getting all the light I need on the road to see and still enough light spilling upwards to be seen by. It’s not a great solution since I’m wasting a lot of the LED’s light, but given a focused optic isn’t an easy DIY hack this seems reasonable so I can use my Dinottes responsibly until they die.

The difference is noticeable and I’ll be modifying both my Dinottes in this way to reduce the blinding effect on other cyclists.

The downside is that you lose a bunch of light power from the LED by simply blocking it. The Euro lights like the Edelux take this light from the upper part of the lens and push it down below the cut off. This not only avoids blinding on coming riders/drivers, but it makes the top part of the beam below the cut off much brighter – ideal since this is the part that must light up the portion of the road the furthest away from the bike. This evens out the light beam so you get equal illumination far away as you do close up.


Unmodified Dinottes...

Are your lights a problem?  Trade bikes with a friend on a dark street and see how your bike looks to others. You can also jump in your car and have a friend ride your bike as you drive past them. If you have no problem when passing your bike on the MUP or street than you don’t have anything to worry about.  You can repeat the experiment on a street with cars and other light sources.  If you don’t enjoy the experience of passing your own bike then it’s a problem you need to deal with.

Can’t you just aim a symmetrical light down so it doesn’t shine in the eyes of oncoming folks’ eyes?  No. The reason is that the light beam from a symmetrical light is brightest in the center and fades to the edges.  If you pointed it down to avoid blinding others the part of the beam you would have left to illuminate the farthest part of the road from you would also be the weakest part of the beam.  This would result in a ton of glare off the road close up and very little light far away.  It would be hard on your eyes and you would have to ride slow to not out run your light’s area of illumination.

The solution I propose in this post is not ideal since it wastes the light that is being blocked by the tape, but it does allow you to shine what remains of the bright part of the symmetrical light beam where you need it further down the road and it reduces the blinding effect considerably.  The fact it’s free is a bonus.  For now it will have to do.

It’s not surprising that a Dinotte light would be illegal for road use on your bike in Germany.  The cops would pull you over and give you a ticket for being dangerous and a nuisance to others.
Just like they would in Canada/USA if you decided to drive around with your car’s highbeams on because they are safer for you.

Since Dinotte doesn’t care about this important issue I’m sad to say I won’t be able to buy any more of their products nor can I recommend them to other cyclists.  If you want a good battery powered or dynohub headlight look at the European options sold by Peter White.  They don’t cost anymore than a Dinotte, but they offer improved performance and safety.






22 responses

14 12 2010

What about putting a small piece of polished aluminum or somesuch behind the tape cutoff. That would reflect quite a bit of the light back through the lens and onto the reflector. Would really depend on the geometry of the reflector, but fair chance you’d end up with at least some of that light making its way, in a useful manner, out and onto the road.

14 12 2010
Ty Smith

Thanks Vic! That is realy helpful!

I have a Dinotte 200 A tailight with a 600L headlight. I also have a planetbike superflash on the back of my helmet. I am always worried I am blinding people who come up behind me, and contstantly check to make sure I have a slight downward tilt.

The other day I came up behind a cyclist who had a supeflash and I commented how visible it was, then asked her how visible I was from the rear.

Well, when she caught up with me a few hundred feet later she told me she was nearly blinded and had to look away from my bike. I looked at my Dinotte and noticed the tilt had shifted, which was part of the problem (constantly happnens).

Anyway, after apologizeing profusely, and re-adjusting, we went another hundred feet or so. She told me then it was still very bright, and not pleasant to look at, but was bearable.

From what you are saying, it appears that the downward tilt helps with folks coming from behind, but reduces its effectiveness. Thanks again for the suggestion. I will give it a try.

Bottom line, I NEED to be visible. I ride daily in downtown San Francisco, rain or shine. I was once hit by a drunk driver, so I probably am a little bit over paranoid, but I can’t help it. However, I don’t want to be a jerk about it.

Dumb question: Are you suggesting this for headlights as well, or just tailights?

14 12 2010

What if you put a piece of reflective material on the back side of the tape to bounce the light back in, and therefore more light out? A mirror would work best, but shiny metal like tin, tinfoil, or even a gum wrapper might work. Just over the light pane of course.

BTW, your blog is not only the best bike blog, but one of the best, most informative, thoughtful, and interesting blogs around. Keep it up.


14 12 2010

@TY – overly bright tail lights are also a problem. Mostly especially in blinky mode since the eye can’t adjust well to the diference in brightness. I would set your rear Dinotte on solid mode and then aim it down a bit. You can experiment by leaning your bike against something and walking up to it with your head at various levels. Find some compromise that is visible, but not deadly for those behind you.

An alternative is the use of moderen reflective material which sends the powerful beam of a car’s headlights back at the driver. They are very effective.

It’s good that you care about others. Being considerate and respectful is it’s own reward.

14 12 2010

@Chuck – thanks for the kind words…you and Ian maybe onto something about lining the tape with a reflector. Not sure that would help, but it might.

14 12 2010
Andy R.

Been worried about this w/ my Dinotte. Been thinking of trying to mount it low on the fork somewhere.

14 12 2010
Ty Smith

Hey Vic!

Last question: I have the 600L light, which is larger than the 200’s, and basically has three bulbs. Do you think your hack would work on this light?

Sorry, I was unable to post a picture for you to see.



14 12 2010

@Andy – mounting a light low is worse for blinding people since it needs to be aimed higher to light the road than a handlebar mounted light. Just imagine you are aiming both lights at the same spot on the road. The lower light points up more.

14 12 2010

Hey Vic – I mounted my 400 lumen Dinotte on an old Petzl strap and used it cross country skiing the other night. Even at the lowest setting, these are uber bright. Approaching skiers also commented that they found them blinding. I’m contemplating adding a filter lense of some sort, perhaps a tinted yellow or amber, to mellow it out a bit. Especially true if its snowing or the air is frosty – you get the wall of white impact of a high beam in the fog.

14 12 2010

@TY – the same principle will work with three LED except you’ll have to make a mini-1/3 cover for each out of electrical tape. Probably not that hard with some sharp scissors.

14 12 2010

Great idea! Even better is too use ‘metal’ tape, as it is stronger and you don’t need to wrap more around the body of the light to keep the front bit in place.

I hope it will stand up to the heat OK …

I just applied some to my Dinotte 600 light, and when I get more time I’ll make a comparison video.

14 12 2010

… yes, only 2 of the LEDs are covered, so the benefits might be minimal. I’ll know more when I do a video test.

14 12 2010
Andy R.

Hmm. I hadn’t thought about that. I was thinking that getting it low would get the main beam below the direct line of sight of oncoming traffic, be it cars, bikes, or peds. Still think it might be worth trying. But you may very well be right.

“@Andy – mounting a light low is worse for blinding people since it needs to be aimed higher to light the road than a handlebar mounted light. Just imagine you are aiming both lights at the same spot on the road. The lower light points up more.”

14 12 2010

Definitely worth trying out anything easy that you can think of. Even if it is ultimately unsuccessful you’ll learn something you can use to your bandit down the road.

14 12 2010

Hey Vik,

Makes folk wonder what happens when you ride in a group and all the people are using multiple PB superflashes. When we leave our weekly meeting (eating pho) we ride home in a passle of bents. My friend will take up rear on lwb high wheel RANS, his SO is in front with Sun ez-3 trike, she has her PB’s mounted so they tilt about to the sides. Since I am usually on a Catrike I do not see the problems of the lights, when I am on Bacchetta it is annoying. Here is a solution that costs about $1.30 per foot, and is easy to mount. We used over 400ft for the parade this past two parades. http://tricolour.net/photos/2010/11/20/01-00-41i1-high.html & http://hpv.tricolour.net/train.html
BTW the horn works at full volume.

PS you can see how the PB’s are mounted here.
Just zoom in and check the top of the trikes, Blackburnpete has the Radbots and his SO has the Planetbikes.

14 12 2010

i had wondered if Dinottes caused this problem in the past, thanks for the tips. another excellent article. i made a few battery lights similar to the Dinotte style – using a metal tube. to solve the problem of glare, i cut the tube (copper) with a 45 degree angle and slightly recessed the optic. the result is very decent – i get a good upper cutoff (handlebar mount) and plenty of brightness (~175lm) for commuting. i am currently working on a dyno version that will have a similar design but will be mounted at the fork crown on my cross check. i will be using an elliptical optic and the same housing design to hopefully achieve a more edelux-ish beam.
you can see a photo of the housing here: http://www.flickr.com/photos/40010668@N06/4458984194/in/set-72157623384052251/
i don’t have any beam shots in that set, and the head-on shots had the lights angled poorly. since then i pointed them much lower.

there has recently been a long discussion regarding lights, angles, strobes, etc, etc: http://bikeportland.org/2010/12/01/ask-bikeportland-can-a-front-bike-light-be-too-bright-43743

14 12 2010

@Brian – when riding home with my GF at night I switch my tail lights and hers to solid mode. That helps a lot.

15 12 2010

Ive mentioned this problem a few times on forums and always get laughed at by folks who think its ok to use a 900lumen offroad light on the roads. Glas there are others out there who think the same,

I have two main lights i use on my bikes, an Edelux fixed to my main commuter and a use my 1000lumen Exposure MaxxD offroad light on my the rest. I did a comparison of the Exposure and the Edelux when i got them and un-supprisingly the Edelux is a lot better to ride on the road with. Even when used on high mode the MaxxD dosnt put as much light on the road when set at the correct angle (As you say, pointing them at the ground does nothing for you).

Looking at other commuters is see daily there is one standout winner in the light stakes, a guy on a folder fitted with a B&M Cyo, damn that thing is good! I can even spot him when he is in traffic and im on the bus, im really impressed with how easy it is to spot without being at all blinding. I hope thats the same for me as essentially the Edelux is just a fancy Cyo, one day ill have to get a mate to ride my bike and get a ‘drivers eye view’ of how i look :0)


p.s. Just as a side note, in the UK we have to stick special light-diverters to our car headlight when we take them into europe (we drive on left, they on right) so our headlights dont dazzle the locals. Its illegal not to. What you are suggesting here is a very similar thing, just wish people would realise!

18 12 2010

My solution to bright lights is to run my Lupine Wilma at 60% on the roads and then turn it down to 10% on the MUPs. Car drivers are used to seeing bright headlights so I don’t think there is a problem on the roads. Running at the low power on the MUPs mean oncoming bikes aren’t blinded.

19 12 2010

@2wheeler – running lights on lower power on the MUP means you can’t ride very fast or you out run your lights. That works if you are going slow.

As far as cars go they are not used to riding down a road with another vehicle running a high beam light. All cars use focused lights with a vertical cutoff when there are other vehicles coming at them.

25 12 2010
B&M Ixon IQ Initial Review… « The Lazy Randonneur

[…] 1W [she normally uses two of these for her commute] as well as my two Dinotte 200L’s….one of which has a DIY vertical cut off hacked on to it.  Just looking at the lights the B&M is a lot bigger.  The Dinottes are smallest with the […]

4 01 2011
That light is spot on « 42 Bikes

[…] the campaign that Vik has been on recently this was good to […]

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