Antique Bicycle

Step 16: The Saddle

The saddle (seat) itself comes from (you guessed it) the old bike.
Some suspension is provided by a steel bracket under the seat which will flex
when you sit down.  I used a steel plate 1 1/2" wide x 1/8" thick x 23" long.
However, I recommend 1/4" thickness instead since mine did flex more
than I anticipated and did not retain its original shape as well.
Bend it in the form of a J and notch off a semi-circle from the long end to accept the
curvature of the headset.  Weld the long semi-circle notched end to the headset
and the short end to the top of the backbone. 
The idea is to give a springy support for the seat.
About 10" from the headset on the seat support steel plate,
weld a steel rod/tube (perhpaps off of the old bike) that will accept the seat of
which you can tighten in place.  This way you can replace the seat with
any other that uses the same standard.
The mounting step is next.