Dynamo Hub FAQ
What is the difference between the Shutter Precision PV, PD, PL, PDX, PLX, SD, and SV hubs?
- PV-8 is for rim brakes. It has an output rating of 6V/3W
- PD-8 is for ISO 6-Bolt disc brakes. It has an output rating of 6V/3W
- PL-8 is for CenterLock disc brakes. It has an output rating of 6V/3W.
- PD-8X is for ISO 6-Bolt disc brakes and a QR15 thru axle. It has an output rating of 6V/3W.
- PL-8X is for CenterLock disc brakes and a QR15 thru axle. It has an output rating of 6V/3W.
- SV-8 is for rim brakes. It is rated for 6V/2.4W.
- SD-8 is for ISO 6-Bolt disc brakes. It is rated for 6V/2.4W
What is the difference between 6V/3W and 6V/2.4W?
- A 3W hub can generate more power.
- A 2.4W hub is slightly lighter.
- A 2.4W hub can be recommended in a few situations:
- For smaller, 20" wheels. A smaller wheel will spin faster for the same forward speed, which makes up for the reduced power rating.
- For LED lighting. LED lights are so efficient that they can produce enough light from a lower powered hub.
- A 3W hub is generally recommended for use with a USB charger. However, the Revolution and Reactor are efficient enough that they can be used with a 2.4W hub, if necessary.
- In general, we recommend a 3W hub. This will give you better charging performance, and a brighter headlight if a charger and headlight are used at the same time.
How do I connect my wires to the hub?
- Schmidt hubs:
- To connect a single device:
- To connect two devices:
- Shutter Precision, Shimano, and most other hubs:
- To connect two devices, you want to connect them to the hub in parallel:
- Strip about 20mm of insulation from all 4 wires.
- Take one charger wire and one headlight wire and twist them together
- Twist together the remaining two wires.
Why does my hub feel "tight" or "notchy" when I turn it by hand?
- From Peter White Cycles: When you hold the wheel or hub in your hand and turn the axle, you'll feel a lot of resistance. There are 26 poles and 26 magnets in the hub. That creates 26 points around the hub shell that the axle wants to settle in, and a corresponding 26 points where the axle doesn't want to be. In the transitions between those points, the axle wants to turn in one direction or the other, to find the point where it wants to settle. As you ride, the hub turns relative to the axle, and 26 times in each rotation of the wheel, the hub wants to turn one way, and then the other, theoretically speeding you up and slowing you down, 26 times per rotation. At speed, the effects of these two forces almost completely cancel each other out, leaving you with extremely low drag overall. It's only when you don't have a lot of mass (your weight) and inertia (your speed) that the effect is to actually retard the rotation of the hub axle. So there's no reason to be concerned about the way the axle feels when turned by hand.