A car and motorbike were involved in the crash near Almondsbury, which took place at around 6.30am.
Three people were taken to hospital and police later confirmed a male motorcyclist in his 60s died at the scene shortly after the crash.
Avon and Somerset Constabulary has appealed for anyone with information to come forward.
Collision investigator Carl Derosa said: “At the time of day the collision happened there would already have been lots of commuters making their way to work.
“We’re keen to speak to anyone who saw what happened or who can tell us about the manner of driving of either of the vehicles prior to the incident.
“We’d also be interested in viewing any dashcam footage of the collision or the two vehicles – a white Volkswagen Polo and a yellow Suzuki motorbike.
“If you can help, please call 101 and provide the call handler with the reference 5219249942.
“If you commute into our force area, perhaps from South Wales or Gloucestershire, please just ask the call handler to put you through to Avon and Somerset police.”
A 21-year-old man was arrested following the collision and has since been released under investigation while further enquiries take place.
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