Having lived in and around the Stour valley for the last 20 years, I can confirm it’s a wonderful area to ride in with many lovely villages and associated pubs. A nice route from Dedham would be via Stratford, Stoke-by-Nayland, Bures, Lamarsh, Ballingdon,Borley, Liston, Long Melford, Lavenham, Brent Eleigh, Milden, Lindsay, Kersey, Williams Green, Polstead Heath, Shelley, Higham, Stratford and back to Dedham. That should be around 60km, I think. If you want to go further, the back roads from Borley to Clare are nice, then, from there via Glemsford, Hartest, Shimpling, Bridge Street, to pick up the route at Lavenham should bring it up around 100km.
Most of these villages have lovely pubs, but I can particularly recommend (in no particular order) the Lamarsh Lion, the Henny Swan, the Lindsay Rose, the Kersey Bell, the Cock at Brent Eleigh, another Cock at Polstead.