Rim Specifications: 
Brand: Dahon
Model: Others
Color: Black
Size (Inch/MM): 451X15C
External width (MM): 20
Internal width (MM): 15
Average weight (GR): 446
Material: Aluminium
Single-walled / Double-walled: Double-walled
Single eyelets / Double eyelets: No eyelets
Number of spoke holes: 20GTS
Spoke nipple size: 14G
Brake surface present: Yes
 
Data for spoke length calculations using the Sapim spoke size calculator: 
Internal diameter of the rim (MM *Not ERD*): 400
Rim thickness (MM): 2
Number of spokes in the wheel: 20
Number of crossings gear side: of your choice 
Number of crossing non-gear side: of your choice 
 
Link to spoke calculator: www.sapim.be/spoke-calculator