I think it was about a 135mm lens on a DSLR on a tripod. Lens center at about 50cm off the ground. Camera far enough back so a single bike fills the viewfinder.

Bikes are vertical, BBs are set at a particular spot. Picture taken of each bike.

Pictures brought into Illustrator, outlines created of each bike. I measured the diameter of each rim and scaled the Illustrator drawings to full size. I cross referenced the seat tube, top tube and wheelbase dimensions to check for accuracy. Everything was within 3mm. Then it is just a simple job of playing with combinations of the outline drawings.