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I run a SON hub dynamo and have recently upgraded my front light (the old light and the dynamo are ~10 years old). The new one is much brighter than the old and has a USB outlet for charging stuff, so I'm very happy with that (Lumotec Eyc).

What I want from a rear light is something like the "superflash" red LED lights, but any kind of blinking would be acceptable. Ideally I'd like one that has both constant and blinking LEDs but I have enough power available to run two, so I'm willing to keep my existing light.

I run my dyno lights constantly, day and night, so having an "off" switch is not necessary (and slightly undesirable), I'd be quite happy with a light that simply flashes whenever power is applied.

But with much searching I have not been able to find anything. I am specifically not interested in the "reelight" things, they will not work for me (and I recommend against them in general, they flash too slowly and too dimly). This thread on bikeradar didn't turn up anything. I suspect part of the problem is that blinking bike lights are not legal in Germany, home of all the good bike light manufacturers.

But I would love a link to one that I can buy, if anyone has one.

(edit in comments) People suggest I DIY, but this question arises from my attempts to DIY. I have built my own bike lights before, and it's hard to make something robust and reliable. Waterproof is a particular issue. Since the original question I have run a light designed for two AAA batteries off the rectified and smoothed dynamo output for a couple of months. Despite my efforts to seal around the hole where the wires went in the light failed after about 3 months of winter riding.

I'm currently running the SeeSense motion sensing battery light and liking the fact that I only have to touch it when I take it off to charge it - it goes into standby automatically when the bike isn't moving. But if I charge it, it stops flashing and has to be manually turned on once charging stops. So I can't possibly use that as a dyno powered light.

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    I concur with the questions unhappy verdict that German law prevents flashing rear dynamo powered lights, Peter White is stronger peterwhitecycles.com/taillights.asp with his "No."
    – Samuel Russell
    Commented Dec 3, 2013 at 2:57
  • Traditionally, blinking taillights have not been provided with gensets because the load of a blinking incandescent lamp would cause the headlight to flicker (worse than it did already). But certainly there have been blinking taillights for battery sets that could be adapted to a genset, and with LEDs the fluctuating load is no longer an issue. (This might actually be a good challenge for some teenager electronics hobbyist -- relatively cheap and straight-forward to do, with readily available parts, other than the housing.)
    – Daniel R Hicks
    Commented Dec 3, 2013 at 4:09
  • @DanielRHicks if I was going to DIY I'd most likely take an existing blinky, remove the batteries and add a 3V regulator or DC/DC converter and run it off the front light output, which is usually a smooth-ish 5V or 6V with modern lights. In my case I have 5V 500mA available from the USB output as well. Although given how many spare blinkies I have, I'd be tempted to leave out the converter and see if one would just run off 6V :) In fact, I might just do that when I get home. A lab power supply is just like a dynamo, isn't it?
    – Móż
    Commented Dec 3, 2013 at 4:33
  • @Ӎσᶎ, why not put several in series ;p
    – Vorac
    Commented Dec 3, 2013 at 9:23
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    @Ӎσᶎ they probably would run off 6V, most of the blinkies run off 2 lithium coin cells in series, giving ~7V. Might need a capacitor though. Even the bigger rear lights use a driver chip that has a reasonable range of input voltages, to provide their current-controlled output. I'm running the PCB of a 2AA rear light in the battery box of a 3AA head torch which I've modded to use 1 lithium AA. so everything runs of 3.6V. Works a treat.
    – Chris H
    Commented Dec 3, 2013 at 10:50

2 Answers 2

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I have an Origin rear light and I've seen that it can be charged via usb and also have the lights on at the same time. If you want to have it powered by a Dynamo, what you could do is have the Dynamo connected to it the whole time on the bike and be lighting at the same time. That could be a way to pull it off and never have to take it off. Also, if you have daylight, the lights could be off and charging so you can use it when the night comes. Good luck.

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Well. I think that you really want this you have to build something youself. Basically you will need a light without a condensator and this circuit. Just add it to the power cable and have fun.

http://www.instructables.com/id/LED-flashing-circuit/

IMHO flashing lights are not optimal because they reduce the ability to gauge distances. A better approach might be to use a really bright rear light, or one with the braking light functionality e.G. the light from Bush and Mueller Toplight Line Plus

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  • The Toplight Plus looks like a worthwhile upgrade to my current, 5-6 year old rear dyno light. It doesn't flash, though, which is what I really want.
    – Móż
    Commented Dec 13, 2015 at 23:31
  • Yeah, sad thing that in Germany flashing rear lights are not officially allowed. I have the Toplight Line Plus myself, and it helps keeping drivers at a distance.
    – Paul Weber
    Commented Dec 21, 2015 at 13:36

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