Schwinn Roadster Owner's Manual page 5

Step 1.
Attach main frame to rear deck. Assemble by aligning the rear
axle against the "C" shaped support at the end of the main
frame, then rotate rear deck assembly so that the attachment
bolt protrudes through the frame. Secure frame with washer
and locknut, and insert the two flanking screws.
Step 2.
Position saddle on frame with carriage bolt protruding through
center hole in frame. Tighten knob onto carriage bolt to lock
saddle in position. Fore and aft saddle adjustment can be
accomplished by removing the saddle-adjustment knob and
re-tightening the knob and saddle in desired hole.
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