If you want to find out more about your Zebrakenko, post up pics of it in the classic and vintage section of this site. Cool old bike pics are always appreciated over there.
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1989 Schwinn Paramount OS
1980 Mclean/Silk Hope Sport Touring
1983 Bianchi pista
1976 Fuji Feather track
1979 raleigh track
"I've consulted my sources and I'm pretty sure your derailleur does not exist"