Police are appealing for witnesses after a single vehicle collision on the B1113 at Redgrave.
They were called around 10.30am on Sunday to reports the rider of a black and red Yamaha, travelling as part of a group of other motorcyclists, had left the road and collided with a hedge.
The man, in his fifties, sustained serious internal injuries and was flown by air ambulance to Norfolk and Norwich Hospital where he remains in a critical but stable condition.
The road was closed while officers dealt with the incident.
Any witnesses are asked to contact the Serious Collision Investigation Team on 101 quoting reference CAD 148 of September 6.