A one-off bike design is a labor-intensive endeavour. The tubing must be cut and fishmouthed with sub-millimeter precision so that all the pieces fit snugly together—no small accomplishment considering there are dozens of crazy angles, offsets, and diameters to factor in. All the pieces of the frame must then be held securely by a jig while the joints are tack-welded. The finish welds must be made carefully to minimize twisting and stress buildup caused by uneven heating. To avoid creating an area susceptible to future corrosion, a welder should be as concerned with the appearance of the inside of the joint as well as that of the outside. For this reason, argon gas is used to displace the air inside the frame during the welding process.
Beyond pure craftsmanship, there are plenty of opportunities for artistic touches on a custom frame. My rear dropouts, for example, pay homage to those of a Wright Brothers bicycle at the Henry Ford Museum. The seat tube is reinforced with a hand-carved lug. Above, my frame builder turns a custom seatpost binder bolt on the lathe.
Continued in part 4…