IT DEPENDS ON THE LOAD, OBVIOUSLY !!!

Just for your information:

- Picture 1 shows Voltage and Frequency at no-load conditions at 20 km/h on a 28" wheel.
- Picture 2 shows Voltage and Frequency on a 12 Ohm resistor at 20 km/h on a 28" wheel.
- Picture 3 shows Voltage and Frequency on a 40 Ohm resistor at 20 km/h on a 28" wheel.

All below data are referred to Shimano DH-3D32-QR hub dynamo.
As you can see all values are referred to 20 km/h, if you go at 40 km/h then frequency will double and voltage will tend to increase significantly.
Cheers.