A german dealer for Old cycling stuff who mostly sells parts for old
town bikes , Heinz Fingerhut http://www.velo-classic.de/index.htm sells
little split rivets for this purpose. They were originally used by a lot
fo german bike manufacturers. Looks like a little chromed nail which is
split. Just insert and pry the two split ends apart with a small
screwdriver or such. Perfect and as original. You can download his
catalogue as a pdf file.
Regards