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I've been searching for the answer to this for a while now and still none the wiser so trying on here...

I've recently bought a second hand hub dynamo and am looking to get some used lights to go with it. I looking for a front light with a switch and standlight function. My question is, do I need a rear light with standlight or not? Logically I think not but can't find any confirmation anywhere.

Thanks in advance...

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If your rear light will not come with standlight function, so (in the options I know) the front light with standlight will not "turn it on" at the rear light. Such lamp is AXA Echo 30 Auto Steady. It has cable to connect it to the hub dynamo connector and output for the rear light. But don't get misleaded. This output only transmits current when dynamo is powering the lamp. At stop there is no output and the front light then consumes the power accumulated in supercapacitor.

You can prefecty use non-standlight taillight in this configuration, but it will turn off immediately after stop.

To have rear standlight, buy one with that option. I strongly recommend battery powered, dynamo controlled light. Current from cable turns it on, but after that it uses batteries and more power can be transmitted to the front light, resulting in stronger beam. Batteries for led taillamp should last for several months, but when emptied, taillamp will be powered by the dynamo, so still working.

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  • Thanks for your answer. So if I understand correctly the rear light won't be powered by the supercapactitor in the front when the bike stops? This is a bit annoying as I'd want one switch and both lights to operate together.
    – itma_its_easy
    Nov 29, 2016 at 0:02
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    @itma_its_easy why would you ever turn a dynamo light off? The drag from a hub dynamo should be imperceptible, so what benefit do you get from having a switch that offsets the extra failure modes of having it?
    – Móż
    Nov 29, 2016 at 0:06
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    @itma_its_easy the model I've suggested has switch ON/AUTO. You cannot manually turn it off, but set on AUTO, if front light will decide that is bright enough to turn of itself, the taillight will be also turned off. For more flexibility I've external switch mounted, between front light and hub connector. Another option is to find lamp with On/Off switch (cannot suggest such among that equipped with standlight)
    – krzyski
    Nov 29, 2016 at 0:26
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    The Busch & Muller Toplight Line Plus is described as having an off switch. e.g. sjscycles.co.uk/lighting/… says "Switch for standlight deactivation"
    – armb
    Nov 30, 2016 at 12:04
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    Having an off-switch probably saves about 20 seconds a day explaining that yes, you know the light is still on on the bike you just left locked up, and no it's not a problem. And at least in the UK, railway platform staff can be quite strict about you not having red lights visible to train drivers. mytrainticket.co.uk/travelling-with-bicycles camcycle.org.uk/newsletters/92/article9.html
    – armb
    Nov 30, 2016 at 12:09
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Thought I should update this just in case anyone's been looking (probably not so much in summer!).

I got a good deal on a B&M Cyo plus. This has a switch and standlight. The rear light connection is switched AC. I bought the cheapest standlight equipped rear light I could find with no switch.

The front light comes on and off with the switch as you'd expect. The capacitor holds charge for weeks on end so you pretty much always have light when you need it.

When you switch off or stop the rear light will stay on until the capacitor drains. This is mildly irritating but slightly less annoying than having to faff with two switches. The other downside is you have to cycle for a while before it'll stay lit when you come to a stop (my first turn on my commute home is only a couple of hundred metres from the office so there's never enough charge to keep the light on).

As for drag, I can feel the change when I flick the switch while cycling. Not significant but enough to make me glad I can switch it off!

Overall I'm extremely pleased with my dynamo powered lights and wouldn't go back. Still can't understand why no one is selling lights as matched pairs with a single shared switch and capacitor though!

Thanks for all the answers.

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  • Great work thank you. Please also click the "accepted" check/tick box on the left side of this answer so SE knows its resolved.
    – Criggie ♦
    Jul 12, 2017 at 21:55
  • I already accepted the other answer some months ago. Should I change it to this one? Sorry don't know the correct etiquette!
    – itma_its_easy
    Jul 12, 2017 at 22:17

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