What an individual wants from a bicycle is a rich and varied subject for conversation.
Sometimes simple; “I want a cyclocross frame that has the same geometry as a 56cm Cannondale Super X. With Enve forks, bolt thru axle, hydraulic disk brakes, 160mm rotors with and lots of mud clearance please.”
Sometimes not; “I’d like a fast road bike that looks industrial and very thin. Maybe with luggage carrying options and maybe mudguards. Traditional but modern with modern components that aren’t ugly. Like that track frame.”
Concepts drawn from these conversations are translated onto paper. 1:1 scale pencil drawings offer an opportunity to stand back and check the line and flow of the frame. Clearances can be checked. Problems highlighted and solved. The final dimensions are transferred onto the jig and tubing assembly can begin.