There is a Schwinn Museum here in the Chicago area with a pretty extensive
collection; they loaned us (Chicago Botanic Garden) some bicycles for a
display on toys for our annual holiday exhibit.  Perhaps they could help.  I
don't have a contact at my fingertips; if you have trouble unearthing them,
call Roger Vandiver (708) 835-8273, the Exhibits Manager at the Garden and he
could point you their direction.