Specifications of the rear hub:
Brand: Shimano
Model: Nexus Inter 7 SG-C3001-7C
Color: Silver
Number of spoke holes: 36GTS
Type of brake: Coaster brake
Number of gears: 7S
Type of axle: Fixed axle 176 MM
Axle included: Yes, without nuts
Type of bearings: Ball bearings
Weight (GR): 1905
Intended use: City

Data for spoke length calculations using the Sapim spoke size calculator:
Total length of the hub (MM): 127
Non-gear side (MM): 31
Gear side (MM): 41
Hub diameter non-gear side (MM): 84
Hub diameter gear side (MM): 84

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