Specifications of the rear hub: 

Brand: BQ
Model: BQ-RH30010
Color: Black
Number of spoke holes: 36GTS
Type of brake: Disc (6 bolts)
Number of gears: HG Body 35 MM = suitable for old type Race (max 10 speed) and all MTB cassettes.
Material des Freilaufkörpers:    Stahl
Material of the freewheel body:    Steel
Freewheel system:    Pallen (6)
Points of engagement:    36
Type of axle: Thru axle Ø 12 MM
Axle included: No
Type of bearings: Industrial bearings
Average weight (GR): 437
Intended use: E-Bike
 
Data for spoke length calculations using the Sapim spoke size calculator: 
Total length of the hub (MM): 148
Non-gear side (MM): 35
Gear side (MM): 48
Hub diameter non-gear side (MM): 62
Hub diameter gear side (MM): 62
 
Link to spoke calculator: www.sapim.be/spoke-calculator