[To straighten a frame, John first has to figure out how it’s bent. To do that, he positions it on his table with the steering tube centered and locked into that anvil of a jig. Positioned in parallel with and exactly 12 inches above the table surface, it serves as the reference point for the rest of the frame. Just as the number 12 plays into our clocks, calendars, and the MB5’s ignition timing BTDC, so to it plays an important role here. Because until the center of the rear axle measures exactly 12 inches off the tabletop, the frame is not straight.