Specifications of the rear hub:
Brand: Shimano
Model: FH-RS400 Tiagra
Color: Black
Number of spoke holes: 32GTS
Type of brake: Rim brake
Number of gears: HG Body 36.85 MM (HG 11) = suitable for all cassettes (possibly with the use of spacer(s))
Type of axle: Drop axle
Axle included: Yes, quick release
Type of bearings: Ball bearings
Average weight (GR): 365
Intended use: Race

Data for spoke length calculations using the Sapim spoke size calculator:
Total length of the hub (MM): 130
Non-gear side (MM): 27
Gear side (MM): 46
Hub diameter non-gear side (MM): 44
Hub diameter gear side (MM): 44

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