The bike left the road at around 10.45am today (Sunday, April 4).
Its rider, a man in his 40s, sustained serious injuries and was being treated at the scene by air ambulance medics.
The road will remain closed between Oldcotes and Blyth for much of the day.
Chief Inspector Andy Rooke, of Nottinghamshire Police, said: “We are working to establish what happened.”
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Anyone with information should call 101 quoting incident 194 of April 4.