Specifications of the front hub:
Brand: Shimano
Model: DH-C6000-3R-N 6V-3.0W Dynamo Rollerbrake
Color: Silver (Polished)
Number of spoke holes: 36GTS
Type of brake: Rollerbrake
Type of axle: Fixed axle 140 MM
Axle included: Yes, with nuts
Type of bearings: Ball bearings
Weight (GR): 957
Intended use: City

Data for spoke length calculations using the Sapim spoke size calculator:
Total length of the hub (MM): 100
Non-gear side (MM): 25
Gear side (MM): 15
Hub diameter non-gear side (MM): 76
Hub diameter gear side (MM): 76

Link to spoke calculator: www.sapim.be/spoke-calculator