that sounds like maybe a mid '80s Sport SS or something. if I was at home I am sure I could track it down better. I do not think * Bs583580 * is a model number. if that number was found on the bottom of the frame by the pedals it is the serial number. the model NAME on Bianchis is normally on the toptube near the headtube.
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“One morning you wake up, the girl is gone, the bikes are gone, all that's left behind is a pair of old tires and a tube of tubular glue, all squeezed out"
Sugar "Kane" Kowalczyk