Reactor Dynamo USB Charger

Sinewave Reactor Dynamo USB Charger in Black (4744650915891)
Sinewave Reactor Dynamo USB Charger in Black (4744650915891)
Sinewave Reactor Dynamo USB Charger in Silver (4744650915891)
Sinewave Reactor Dynamo USB Charger in Silver (4744650915891)

Reactor Dynamo USB Charger

Regular price $210.00
Shipping calculated at checkout.

The Sinewave Reactor is in it for the long haul. It's a dynamo-powered USB charger that fits seamlessly into the threadless steerer tube of your bike for handy yet unobtrusive access to the port. Keep the good times (and all your electronic devices) rolling for every long ride you never want to end.

The Sinewave Reactor differs from other dynamo-powered USB chargers on the market in several ways. First off, it's got best-in-class efficiency, meaning no pedal stroke goes to waste. It starts charging your device at a speed of 5.5 km/h and delivers as much power as a wall socket at 14.4 km/h, with overcharge protection to save your device's battery from too much input at speeds higher than 35 km/h. With a standard USB plug, it can charge pretty much anything with a USB-compatible charging cord, including GPS devices, bike computers, phones, portable speakers, battery packs, and headlights. 

The Sinewave Reactor is compatible with all dynamo hubs and bikes with 1" and 1-1/8" threadless stems. It maintains a low profile, with only 9.8mm of the CNC-machined stem cap that houses the USB port sticking out above the steerer tube and a pass-through for the 6mm bolt. All electronics are potted in epoxy for full weatherproofing and vibration resistance, and the connections are all gold-plated for anti-corrosion protection. The Reactor comes with a 36" wire to connect it to your dynamo hub.  

Proudly made in the USA, the Sinewave Reactor Dynamo USB Charger will see you through, no matter how long you're out riding!

  • Sinewave Cycles Reactor Dynamo USB Charger
  • Keeps your USB devices (phones, GPS, bike computers, speakers, headlights, battery packs) charged up at all times when paired with a dynamo hub
  • Provides as much charging power as a wall socket when travelling at just 14.4 km/h
  • Replaces the stem cap on 1" or 1-1/8" threadless stems with a USB charging port - Compatible with all dynamo hubs
  • Overcharge protection keeps your USB device's battery safe when travelling at over 35 km/h
  • Potted in epoxy for full waterproofing, with gold-plated connectors for corrosion resistance
  • Comes with a 36" wire to connect the Reactor to the dynamo hub
  • Available in black or silver
  • Made in USA
  • Reactor Dynamo installation instructions here
    POWER Dynamo-powered - Max output 1 AMP
    CHARGING SPEED Starts charging at 3.5 MPH (5.5 km/h)
    Full charging at 9 MPH (14.4km/h)
    WATERPROOF Yes - Epoxy potted, gold-plated connectors
    REMOVEABLE OR BOLT-ON Bolt-on, theft-resistant
    SUITABLE FOR City Bikes, Hybrid Bikes, Touring Bikes, Trekking Bikes, Road Bikes, Mountain Bikes
    USAGE 1" or 1-1/8" threadless stem mount
    WARRANTY 1 year from purchase date
    Curbside Cycle Free Shipping


    Canada: We use UPS, Purolator, Canpar or Canada Post within Canada. All applicable Provincial Taxes are charged at checkout. Orders may take 1-2 business days to process. A tracking number will be provided by email.   

    USA:  We use UPS, UPS Mail Innovations, or Canada Post/USPS in the USA. No US or Canadian Tax is charged at checkout and all cross-border Fees and Duties are prepaid so there are no surprises. Orders may take 1-2 business days to process. A tracking number will be provided by email.  

    *Does not apply to oversize items.

    Supernova Logo
    Sinewave Cycles Company History: Based in Cambridge, Mass., Sinewave Cycles' goal is to design the best American-made dynamo front lights and dynamo-to-USB chargers for use "in the middle of nowhere" far from the help of bicycle mechanics. The founder Dave Dean, electrical engineer extraordinaire, loves cycle touring and randonneuring and needed a light to support his trips, so he designed it himself. Their products are proudly made in the USA and are designed for use in the foulest weather and rough handling thanks to their metal construction, gold-plated connector components, and electrical guts fully encapsulated in waterproof epoxy

    What devices can I charge with the Reactor?

    The Reactor output is a standard USB charger (5V), and can provide up to 1 Amp. If your device can charge from a standard USB connector, it should be able to charge from the Reactor. This includes iPhones®, smartphones, GPS devices, USB battery packs, headlights, rechargeable speakers, etc.

    How fast do I have to ride to charge my phone?

    With a hub generator, charging starts at only 3.5 MPH (5.5 km/h), although this can depend on your device's ability to trickle charge. At only 9 MPH (14.4 km/h), charging is as fast as a wall-powered charger.

    Will I damage the Reactor when I ride fast?

    No, you will not. Many dynamo-powered electronics suffer from this problem. Even products that claim to be “protected” will actually draw extra power and heat up when you go faster than about 20 mph (35 km/h). The Reactor has a novel, integrated protection circuit that will not draw extra power or heat up at any speed.

    Is the Reactor weather-resistant?

    Yes. The Reactor is waterproof and can be left out in the rain.

    How can the Reactor be so waterproof with an open USB connector?

    First, the electronics are fully encapsulated in epoxy. This means that water can not touch any of the components, even if it gets past the connector.
    Second, the USB connector itself features gold plated contacts that will not rust or corrode.

    Can the Reactor withstand shocks, vibrations, and off-road riding?

    Yes. The electronics are fully encapsulated in epoxy. In addition to providing complete protection from the elements, this makes the Reactor extremely resistant to bumps and vibrations.

    Why does it take ten seconds for charging to begin?

    Some devices, such as the iPhone, require a minimum amount of power to charge correctly. If charging begins before input power is sufficient, the device may refuse to charge. The 10 second delay gives you time to reach a minimum speed. This allows you to charge an iPhone® or other devices that would not otherwise charge correctly.

    Does the Reactor have a built-in battery?

    No - and this is a good thing. Most chargers that include a "cache battery" do so because they are not efficient enough to directly charge a phone - they must slowly charge a battery, then charge the phone from the battery. This adds further inefficiency to the system, as well as a delay while the internal battery is charged. The Reactor is able to directly charge your phone, making the cache battery unnecessary.

    Some chargers have a larger built-in battery, meant to store a large amount of energy. There are several reasons we don't like this system:

    1. Product lifetime. Batteries wear out. Even the highest quality lithium ion battery is rated for about 3 years from manufacturing, independent of how much you use it. There's nothing in the Reactor that wears out. When you build up a touring bike you select parts based on reliability and durability first, and everything else second. We want the Reactor to be the same way.

    2. Efficiency. The extra steps to charge the battery, then use the battery to power the output is a significant hit on efficiency. Most users directly charge their phone, and the extra conversion steps mean wasted energy.

    3. Flexibility. A product with an internal battery is stuck with that one battery, which may be too small for some users and too large for others. There are many USB battery packs available in all sorts of shapes and sizes and capacities. The freedom to use a battery that fits your bike and your tour is lost when an internal battery is used. This also allows the Reactor to be as small as possible.

    Will the Reactor work with my dynamo?

    Yes. The Reactor can be used with any hub, bottle or spoke dynamos. Any standard 6V/3W dynamo will generate enough power for the Reactor to charge your device. We have also had good results with 6V/2.4W dynamos. The less-common 12V/6W dynamo can be used as well.

    How do I connect the Reactor to my dynamo hub?

    This varies by dynamo type and manufacturer. The exposed ends of the wire can be used to connect to any dynamo. Consult your dynamo’s instruction manual.

    Can I connect the Reactor to the taillight output of my headlight?

    This is not recommended. The main reason is that, since the taillight is turned on and off with the headlight, the Reactor will only be powered when the headlight is on. In most cases you want to use the Reactor when the headlight is off, and vise-versa, and this is not possible when using the taillight output.

    Can I use the Reactor and my lights at the same time?

    Yes. Simply connect the wires to the dynamo along with the headlight cable (in parallel). The dynamo power will be shared by the Reactor and the headlight, so we advise unplugging your phone/gps/device being charged to ensure that your headlights are at full brightness. You do not need to disconnect the Reactor - it draws practically zero power when not charging a device.

    Can I use the Reactor with an e-bike battery?

    Yes. The Reactor works with e-Bike batteries up to 48V. The Reactor has no polarity to worry about when connecting to a battery.

    Can I use the Reactor with a regular battery?

    Yes. The Reactor works with any DC input voltage above 6V, up to 52V. This means the Reactor can be used as an emergency charger with a 9V battery, car battery, 4 AA or AAA batteries, etc.

    Can I use the Reactor with a solar panel?

    Yes. A solar panel generates DC voltage so the Reactor will work with a solar panel the same way it works with a battery.

    Will the Reactor damage my device?

    No. The output is fixed at 5V, so unlike chargers with an “adjustable” output, you can not accidentally damage your device with incorrect settings. The high speed overload protection circuitry will protect the Reactor and your device from the high voltage generated when you go fast.

    How much current does the Reactor draw when it's not in use?

    By itself, the Reactor draws only 1.6mA.

    Do you recommended any specific USB battery packs?

    Most USB battery packs are very flexible and do a great job charging from the Reactor, even at low speed. If you simply want to charge a battery while riding and use it later to charge your devices, almost any battery pack can be used.
    If you want to use your battery like a buffer, and connect from Reactor to battery and battery to USB device, you need a battery that supports 'pass through charging'. This feature is not always clearly advertised and is implemented differently by different brands.

    How can I test that my Reactor is working? 

    Wiring and connection issues are the most common causes of problems. Because the Reactor can be powered by a DC source it can be tested independently of the wiring and the rest of the system:

    1. Get a 9V battery (fresh, if possible)

    2. Disconnect the Reactor wires from the dynamo or any other devices.
    Plug a USB device into the Reactor USB connector.

    3. Touch the Reactor wires to the battery terminals (polarity does not matter).

    4. After the usual 15 second delay the USB device should start charging.
    If this test works, the Reactor itself is OK and any problems lay elsewhere, most likely the wiring, connections, or dynamo. 

    What if I have a question that isn't answered here?

    Please email Sinewave at

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