If by "Port of Venice" you mean Mestre, it's a busy industrial city with little to recommend it for much of anything, especially biking. There are bike paths and bike-friendly back roads along the Riviera del Brenta (along the Brenta river). It goes past many villas built during the Renaissance. People pay for boat tours to go by these villas. You could finish up in Fusina, which has ferry service to Venice and the Lido islands.
There's good riding around Bassano del Grappa, NE of Verona, though perhaps too much out of your way.