i dunno about you guys, but the only tricycles i can think of that little kids ride don't have a chain at all... the pedals were actually attached to the axis of the front wheel... this applies to not only the trikes that were made of metal with actual tires and spokes and chrome handlebars, but also to the tonka/hot wheels trikes made almost entirely out of plastic...
now you don't even need a chain! =D
(if you do still want one though, do a google search for tank tread animation cause it's the same premise)
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