Review Cycle2Charge USB charger

Review Cycle2Charge USB charger

with 15 Comments

Recently I came across the Cycle2Charge V2. This little device is – combined with a dynamo – a USB charger for your bike. It replaces the stem cap of an Ahead headset and is wired to a front hub dynamo. Inside the Cycle2Charge energy from the hub is converted to USB voltage (5V). Plug in any electronic device that can be charged via USB and start cycling. Simple as that!

The Cycle2Charge is a direct competitor to Supernova’s The Plug III (159 euros) and the Sinewave Reactor (220 USD) but with one distinct difference: its price tag of only 56,90 euros. With a price roughly a third of the other two devices only one question came to mind: does it work?


The looks

The Cycle2Charge is a bit bulkier than two other devices mentioned above. The dome shape is a bit wider than the stem. But Cycle2Charge has a very good reason. If the charger is not in use you can twist the top to hide the USB port to protect it against rain and dirt. No need to fiddle around with small rubber dust caps or something. One cleaver feature!

The casing is made out of metal and feels really sturdy. In my enthusiasm I totally forgot to weigh the thing before installing! More about that later on.


But does it work?

After installing (see below) I took it for a short spin. I switched on my Garmin and plugged a short USB cable into the Cycle2Charge. A beep and the small battery icon told me it was charging. Woohoo!

Don’t woohoo too much yet, because now another question comes up: how slow can you go? This is important because some devices stop working at slower speeds, meaning your device doesn’t charge anymore, meaning your Garmin starts beeping annoyingly every time you take a corner, head for an intersection, take on a climb and so on.

How slow can you go?

I started slowing down. 20km/h … 19 … 18 … 17 … 16 … 15 … still charging! … 14 … 13 … 12 … wow! … 11 … 10 … then it stopped. Still charging at 10km/h, another big woohoo!

To prevent damage to the electronics the Cycle2Charge has a top limit, or overvoltage protection. I went to one of the few climbs in my area and started descending. 30km/h … 40 … 50 … still charging. As it turns out there is not an actual top speed where the charger stops working. Instead all the ‘extra’ power is cut away before it enters the critical electronic parts, to put it in my layman’s terms. So, no reason to take it slow on those descends!

Easy install

You don’t have to be a electrician to install the charger. Here is a how-to:


This is basically it: a wire, the Cycle2Charge unit and a bolt. Also included are three zip ties and a manual.


Remove the stem cap. You don’t have to loosen the stem bolts below. Take off the cap and bolt. You don’t need these anymore. Put the wire through the star fangled nut (or: the best named bike part).


Leave the white connector stick out for about 3 centimetres.


Take off the dynamo connector (mine is a Shutter Precision) and open the connector.


If you already have a head light installed, twist the front light’s wire ends and those of the Cycle2Charge together. The polarity doesn’t matter. Reassemble the connector and put it back on the dynamo.


Now click the white connector in the Cycle2Charge unit. Decide which way the USB port has to face. Here it is facing backwards but when there is enough space above the stem facing to the front might be a better option.


Hold it in place, put in the bolt and tighten like a normal stem cap. Now secure the cables to the fork with the supplied zip ties. My advice would be to shorten the cable only when you are confident everything is working properly.


About Cycle2Charge

Dirk Langhuber is the person behind Cycle2Charge. I asked him how it all got started. Dirk: “At first I developed the charger for my own needs as I planned a cycle tour through Lithuania and Latvia. As this tour was a camping tour and I wanted to use my mobile and GPS anyhow, I needed some source of energy to charge these devices. The first handmade prototype worked out fine, so I decided to improve the design and usability to offer it to other cyclists as well.”

About the current second generation version Dirk mentions: “At the beginning of last year I optimized the electronics of the charger further to improve the efficiency of the voltage converting and I also improved the point of highest efficiency for touring cyclists. In other words I focussed on the daily use cases and tried to get as much power out of the charger at travel speeds around 20km/h and did not try to improve any datasheet values in terms of maximum output that can only be achieved at speeds above 30km/h. This optimized version is called Cycle2Charge V2.”

In conclusion

The Cycle2Charge is a USB charger you get easily accustomed too. Turn your bike into a USB power generator and charge your phone, camera, navigation device and so on. It is a bit bulkier than the competition but adds the easy ‘twist to hide’ feature. With a price of only 56,90 euros it is a real bargain compared to the other two well-known stem cap USB chargers. Recommended!

Pros: affordable price, ‘twist to hide’ protection, works at 10 kmh and up

Cons: bulkier than competitors

Note: The fork must have a hole for the cable to run through. Don’t even think about drilling a hole in your carbon road bike fork. 🙂 (in English)

56,90 euros (ex. shipping)


Follow Stephan van Raay:


Photographer on a bike, enjoys long distances onroad, varied with the occasional offroad track.

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15 Responses

  1. Roy
    | Reply

    Great review. Someone is finally selling these in the US on eBay, just purchased mine for $100. I figured with the additional 20 euros in shipping, I’m paying nearly the same amount but without waiting a month for it to arrive from Germany.

    Link is here:

    • Stephan van Raay
      | Reply

      Thank you, Roy! I’m glad my review was helpful to you. $100 is still a decent price for this piece of equipment. I also noticed this someone also stole one of my photos for his eBay-ad … argh sellers 🙂

  2. Beatriz
    | Reply

    Hi, I’ve installed the cycle2charge device at my bike. I’ve been riding for about two hours, speed between 17 and 27 km/h. My mobile phone did not only not load, in spite of indicating it was loading, but in deed, the battery went down during the ride. Can you give some hints here? Thank you

    • Stephan van Raay
      | Reply

      Hi Beatriz,
      That’s strange. Your speed should be suffice to charge. Did you try another device like a Garmin for example? If none of your devices are charging, check if the white connector at the bottom of the charger is still plugged in, the wires are intact (the star fangled nut has sharp edges!). Also the wires in the dynamo connector shouldn’t contact each other to prevent short circuiting. If all is installed properly and it is still not working I suggest you contact Cycle2Charge. Hope that helps!

  3. Arthur
    | Reply

    Cycle2Charge v3 works really good… When your light is off. But when you ride at night, you have really really small lights (well, almost none – front and rear) and… no charging. Worst is that even if you don’t plug something to charge, you don’t have lights…
    Good but unfortunately not perfect !

  4. mrez
    | Reply

    Hi, Have you tried to add a small battery pack to this (inside the body)? I think it would be perfect but sadly I am not sure how this can work if it should!

    • Stephan van Raay
      | Reply

      Sorry for the late reply. No, I haven’t tried that. I charge all my devices during the day, including a large usb battery pack. It’s probably not the most efficient, but it works for me. And I like to keep it simple. Electronics failing is very annoying, I think.

  5. Arnaud
    | Reply


    Thanks for your review is it still working fine 3 years later?

    • Stephan van Raay
      | Reply

      Actually, I’m on my second one! With the first one I ended up in a severe storm. I noticed too late I left the usb port open. So that was entirely my own fault. Apart from that I’ve never had an issue with both of them!

  6. Giovanni
    | Reply

    Hi Stephan, thank you for your detailed and helpful review!
    Could you please specify:
    1. features of your dynamo;
    2. if the device is correctly working when used at the same time of lights.

    • Stephan van Raay
      | Reply

      Hi Giovanni, thanks!
      The dynamo I use is the Shutter Precision PD8, the disc version of the 8 Series:
      I charge all my devices, including battery pack during the day, and use it for lighting in the dark. Never at the same time.
      Hope this helps.

  7. Marco
    | Reply

    Hi Stephan,
    thanks for the great review! I used my v2 for a couple of trips over the last 4 years but I have recently noticed that it generates a lot of resistance also when it is not charging anything. Now I wonder if it has been like this since the beginning or something went wrong, maybe some water got inside the cap. Do you notice any difference in rolling resistance with and without the cycle2charge?

  8. Luc
    | Reply

    Stephan van Raay:

    Are you still using it?
    You wrote that you are using dynamo both for charging and light, but never at the same time. Do you have some switch (if so, is it something built by you or are have bought it somewhere: what/where?)? Or maybe are you unplugging the cables of charger and plugging in cables for lights, when you want to start using lights (and were using charger)?

  9. Richard Riley
    | Reply

    Very good article.

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