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I bought online a Cube Nuroad Race FE 2021 that comes full with fenders and dynamo lights. The front light is the Supernova E3 Pure and, although not stated clearly on Cube's site, the rear light should be Cube Pro-D dynamo mudguard rear light that includes stand light function according to Cube's site.

Now when the bike moves, both lights shine brightly and all is well. When I stop however (even after a long ride), the front stand light works, but the rear stand light does not. I noticed however a very very dim light in it.

I have asked Cube for help, but I am really wondering what is going on and whether there is a way to troubleshoot this. I know that this is not a bad component issue, since other users report the same behavior.

Also a minor note: I checked Supernova's manual and the only interesting thing I found was that the rear light should NOT be grounded to the frame. I checked it and could not see any ground cabling on the rear.

There are two wires going back to the rear light.

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  • The bike is brand new, and as a Cube customer you are almost certainly in Europe, likely Germany. Let Cube deal with this problem. It's covered by European consumer rights.
    – gschenk
    Oct 12, 2020 at 23:04
  • Asked the shop I got it from. They said that there is no stand light on this bike. Pretty much a disappointment for a 1.8k bike! I have asked Cube as well but they have not replied for several days now. Note that on their site, Cube does not claim that there is stand light functionality in the rear light, so I cannot make any claim unfortunately.
    – Kostas
    Oct 14, 2020 at 7:46
  • Well, than everything is all right with the bike and the light, only your assumption was wrong. Simply buy the stand light and install it?
    – gschenk
    Oct 14, 2020 at 9:01
  • Did you fixed that rear light in your Cube? I have same problem. Rear light stopped working. I have Cube Nuroad Race FE 2021.
    – Rafal
    Sep 17, 2021 at 0:17
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    @Rafal see my answer below.
    – Kostas
    Sep 18, 2021 at 19:15

2 Answers 2

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It would seem likely there's a problem with the rear light's capacitor. I'm a generator light user and nerd but not a real electronics person, so maybe someone else can answer better, but my understanding is that what you're seeing (everything works but the standlight is dim) indicates a capacitor that's barely functional. You could open the light up and try following standard methods to test and then replace it. Dropping in another fender mounted tail light is also an option, but they each have their own needs for where to drill the holes to get a good angle, so you might give up some of the integrated look of the stock light on that bike.

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    Thanks for the answer. It actually looks that other users of the bike have the same issue, so it is either a bad assembly, or simply that the rear light somehow does not work with the front light.
    – Kostas
    Oct 11, 2020 at 18:07
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    Given this light has issues, I'd absolutely recommend a second rear light, autonomously battery powered too.
    – Criggie ♦
    Oct 11, 2020 at 18:34
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    I thought that when the standlight went on my B&M Secula+ that got immersed in water. Replacing the capacitor didn't help, and the old one tests fine. I'm not saying it definitely isn't the supercap this time, but it's by no means certain
    – Chris H
    Oct 11, 2020 at 19:54
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    @Criggie: I spent 200 euro more and added about 1 kg of weight just so that I do NOT care about batteries. So sing battery lights does not make sense, unless I strip and sell the dynamo wheel and the dynamo lights.
    – Kostas
    Oct 12, 2020 at 8:06
  • @kostas you're in Europe then, where Dynamos seem to be much more accepted. In 5 mins I can't even find a seller in my country listing a price for a Son dynamo.
    – Criggie ♦
    Oct 12, 2020 at 11:13
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I eventually contacted Supernova and, contrary to Cube, they replied almost immediately. They said that in order to get rear stand light functionality with their front light, you have to use their rear light only. This is what I did actually. I bought their rear light that mounts on the seatpost and connected it to the front light by cutting the wire that went back to the mudguard light. Honestly, this is a much better solution. The rear light is very bright, it is now elevated for better visibility, it is minimal and good looking and stand light works. The plus is you can get rid of the mudguards in Summer without losing the rear light!

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  • Thank you for coming back and providing closure - remember to mark this as the "accepted" answer.
    – Criggie ♦
    Sep 18, 2021 at 22:14
  • That sounds like the standlight capacitor for the rear is in the front light. That's not common, and would be enough to put me off Supernova lights - htey're not driving the rear in a standard way. Indeed on my tourer I can turn off my front (Axa) light and my rear switches to a fairly bright standlight mode.
    – Chris H
    Sep 20, 2021 at 12:02
  • I think so, yes. This is why the rear light can be so small. As I said, it does look neat.
    – Kostas
    Sep 21, 2021 at 19:49

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